You can accidentally learn all sorts of things while poking around the Internet. On a totally unrelated search, I happened to stumble across the fact that April 2 is Peanut Butter and Jelly Day.
I like simple foods, and it doesn't get a lot simpler than the peanut butter and jelly sandwich. I'll have at least a couple every week, often more. I've even been known to go out of my way in the Detroit airport to hit the PB&J shop there, although sadly I think it closed down last year.
I prefer the basic PB&J sandwich: smooth peanut butter, strawberry or grape jelly, sandwich bread. People will make all kinds of additions, though. Grilling, deep-frying, multiple types of peanut butter and/or jelly, interesting breads, bananas, potato chips, and so on. And it's not just sandwich day. I've seen recommendations for PB&J used with cupcakes, waffles, pancakes, crackers...all kinds of variations.
There are people who use peanut butter and jelly as more than just a food. The PB&J Campaign is a project within A Well-Fed World, a group concerned about providing food for the world in an environmentally-friendly manner. The campaign uses the PB&J sandwich as an example of how eating more food products from plants and fewer from animals is a smaller environmental impact. Environmental impact isn't my main reason for eating PB&J sandwiches, but it's a nice bonus.
It's not clear from my cursory Google searching where Peanut Butter and Jelly day started, but it sure seems to have caught on. Even has a Twitter account. Happy to do my part to celebrate.