(Disclaimer: My experience is solely based on Sonoma County and San Francisco area habits. It doesn't cover any other parts of the country, be it similar or totally different)

Food in America is extremely important, one could go as far as saying that it is a religion based on how strongly people feel about it. It's a centerpiece, a pièce de résistance of every event and occasion. There might be happenings taking place because of food, but an event hasn't gained significance, attention and prestige if it doesn't have a feast lined up. Food authenticity, quality and thirdly, quantity keeps people in or kicks them out of business. "Anything goes" when it comes to food is a no-go. Every occasion has its very own dishes served (e.g. turkey on Thanksgiving Day, hot dogs on the 4th of July, chicken wings on Superbowl, etc.), as well as every meal can consist of certain items (e.g. French toast is suitable for breakfast and brunch, but definitely is not served for dinner, cupcakes are for dessert, but not breakfast, ahem...). Snacking is also a really serious matter and activity (and also, industry), ranging from fruits, nuts ("trail mix") and crackers to candy bars, mozzarella sticks and toasts or apples with peanut butter, munched on at any time of day, usually between meals, on hikes, at the beach and in the car.
There are 5 possible meals: breakfast, brunch, lunch, snack, dinner. Variations may include a second breakfast, and to be fair, snack is not really a meal, but I believe most of Americans would agree that it is an important part of their day, so we might as well count it, too; and lastly, there's dessert...

BREAKFAST
According to my research, if done properly, it is America's favorite meal :-)
Some can only afford this luxury on a weekend, but a lot of Sonomads happen to have flexible schedules, so it becomes almost a daily routine to take your time and ingest your breakfast rather slowly, over the daily paper (aka newspaper). It is not an uncommon sight to spot a person sitting at a table, soaking the morning rays of sun, sipping on their tea or coffee, and orange juice, eating whatever it is that day, and reading the paper for an hour. It seems like the time has paused, like no one is in a hurry and as if the world is going to have to wait for its turn to get their attention...
Breakfast is sacred, it is the most important meal of the day and it needs to be taken seriously. You need to have breakfast before you go out of the house in the morning, and if you skip that part, make sure to stop and get some breakfast on your way (bakery, restaurant/diner, store). It is not a meal not to be had. It is a meal to be cherished, enjoyed and one that nourishes and gives you strength for a good start of your day.
Some places go as far as "serving breakfast" all day or until afternoon hours -- as sign of an exceptional love and relationship the Americans have towards the very first meal of the day.
Breakfast then, depending on the state of your mobility and how much time you are willing to contribute to it, will vary. Blueberry muffins, English muffins, waffles, pancakes, French toast with unlimited amounts of maple syrup, of course; cinnamon rolls, scones, bagels, Danish, cereals... Eggs: scrambled, Benedict, hard boiled, poached. With or without bacon/smart bacon, sausages and potatoes. Tofu scramble. Smoothies, orange juice, tea, coffee, milk. Seasonal fruit. Never-ending amounts of choices!
Breakfast is caloric, sweet and savory, and sure not to be missed!

BRUNCH
Nothing tastes better after a night of partying (be it random clubbing, big birthday party that ran kind of late, New Year's Eve, etc.) than brunch! Every child will attest to that (once they reach the appropriate and legal drinking age).
A word is a port-manteau of breakfast + lunch, and extends its significance to what is served during brunch time. It is nothing more (and nothing less) than select breakfast and lunch items plated together and eaten between 11am and 1pm. It could be organized in the form of self-served buffet (that can be seriously overwhelming and guarantees overeating), or one including waiter service.
Met your family for brunch? How about a French toast with fruit coulis, a fruit salad and eggs. Or a bagel with cream cheese, potato hash and a sausage. Or a piece of baguette with jams, a green salad and orange juice... Options seem endless with this 2in1 meal, and all sorts of eaters will find suitable items for their liking and diets. Brunch is a live savior, and an ideal way to keep celebrating whatever you started the night before. It also is a good combo meal, as it will satisfy the breakfast lovers and the lunch people. Mimosa, anyone?

LUNCH
Samwiches!!!! If you say sandwich, I say sourdough rolls, yellow mustard, mayo, pickles, red onion, a bunch of shredded lettuce, tomato and your choice of other toppings (cheese, turkey, tofurky, other meats and meat-subs). Lunch could be then a quick grab ("Let's grab some lunch! How much time do you have? Not much, but I can eat a sandwich..."), or a more extended full-sized meal. Stop by a taqueria for a burrito or at a deli, for the gourmet sandwich experience (cornichons, anyone?) Forget Subway. Giovanni's, Traverso's or other gourmet deli is where it's at! Sushi for a business lunch or with family. A café in town may offer some grilled-cheese (sandwich) with soup or salad. Pastas, pizzas, and leftovers from last night's dinner are all acceptable. Lunch is a freestyle meal, not constrained by a lot of conventions.

DINNER
Dinner is served awfully early in this country (and why that is? Maybe because you need to have enough time and room for dessert -- an-almost-meal-on-its-own?!). Some restaurants close at 9pm, and usually you can get dinner starting around 4-5pm.
Dinner is another one of those important meals... It is usually dinner you have with your family on Thanksgiving Day, Christmas and other important celebrations. Families might eat all their meals separately during the day, but everyone gathers faithfully around the dinner table in the evenings: mothers call their children to come in for dinner and set the table, parents come back from work and sit at the dinner table with their kids... There is a feeling of serenity surrounding this meal, it is not to be eaten fast or ruined by excessive snacking beforehand (save the cereal bowl for dessert, if you will, or you will spoil your dinner!). It is a significant chunk of family time, as a lot of conversations take place during the meal: as you share the food, you talk about how your day went, your plans, and other stories. It is somewhat sacred for families to meet together for dinner. It is a meal you don't skip on, like you wouldn't be skipping on your family. It is the family meal, and you'd better have good excuses if you don't show up for it! So what's for dinner, Janes and Joes wonder everyday. You name it: in this part of the country, it can be pretty much anything, ranging from French dishes (tarts, soups, boeuf Bourguignon), through German (Bratwurst and other sausages), Scandinavian (meatballs!) and Italian (pizzas, pastas and lasagne), Asian of all sorts (Japanese, Chinese, Vietnamese being the dominant cuisines, offering different rice and noodle dishes, soups and appetizers), Mexican (tacos, tortas, enchiladas, and everything in between) to American (chicken wings, steaks, BBQ) and wherever the chef's imagination will take you... American dinners are as varied and rich (culturally) as the society is.
When going out, it is a common practice to order appetizers, as to initially calm the monstrous hunger you unwisely came to the restaurant with. You are brought your drinks, your appetizers, and then, with a peace of mind and piece of food, you can order the main course, called the entrée... How long does it take to get used to the entrée being the main dish and not a starter? Quite a bit. A few months to a year. And internally, it still doesn't make any sense to me... But hey, this is 'Merica! :-)

DESSERT
And then desserts! Pies, ice creams, cupcakes, cakes, cookies, brownies, tarts, tartlets, chocolates... A wide variety of desserts. It goes as far as saying that you need a special, separate stomach, just for dessert; that means that no matter how full you are, you will always have room for dessert (how convenient and practical!), and you will never say no when it's being served.
When it comes to pie: it is as American as the Statue of Liberty, Golden Gate Bridge and the Dream. If you've been to the States but haven't tasted the real apple pie, it is as if you've never come... You need to come back and have a piece or two, à la mode, that is with vanilla ice-cream, lightly warmed (seems like a very traditional way of eating pie. How fashionable it is? I guess it's timeless, so mode-proof!). Mmmm... Just the memory of it warms you up -- for years! Addiction guaranteed, and a very gourmet experience that every gourmand dreams of.

SNACKS and OTHER FACTS
Peanut butter in itself is an American legacy and a national treasure along with maple syrup. Peanut butter and jelly sandwiches (or PB&Js) are well-known to every American kid and their ultimate favorite, and are equally loved by adults. It seems like there is nothing else like it anywhere else in the world, and one has to admit, the best peanut butter in the world can only be found here, too. Creamy, crunchy, salted or not. In sandwiches, with apples or just by the spoonful. The America can be divided into red and blue states, but the peanut butter flows in every village, town and city in this country.

Maple syrup is either mainly produced in the province of Quebec in Canada (more than 80% of the world production) or the state of Vermont (although a few other eastern states are also producers). Despite its foreign provenance these days (and the eternal animosity between the two countries), and its Native American provenience, it's considered a national treasure and a necessary addition to the real American breakfast (be it French toast or Belgian waffles, but not English muffins...).
Some people use its cheap alternative, or the pancake syrup (it seems like "alternative" implies that the latter is more or less equal to the former, which is definitely not the case here. The real maple syrup is the best in its category and there is nothing that comes even close to it), but once you've tried the real deal, you will never go back!

The latest in portable food news are food trucks that have all of a sudden rose from the ground and took over some parts of cities and parks. Sebastopol has its very own trucks that have their scheduled times of appearance in a couple of preannounced placed: lunch is served at the O'Reilly parking lot, dinner at the Regal Park. Of course, the ice cream trucks have existed for quite a while now (and are almost passé), but it seems like here people are still riding this wave, and doing it pretty well. There appears to be more and more pizza trucks and trailers, which obviously is a good sign for all the pizza lovers out there, especially that a lot of them tend to serve good food and some even the Napoletan style (which is far more superior than any other one).

Image: Copyright New Yorker, December 3, 2012, Farley Katz