It is said that American soldiers in World War II were given peanut butter instead of meat due to enforced rationing. Jelly was added to the peanut butter to make it taste better and the PB&J was born. When soldiers returned home the sale of peanut butter and jelly soared.
Nut butters come in different variations such as almond, cashew, walnut, hazelnut (nutella) and can be used to make sandwiches similar to peanut butter and jelly.
Some variants include the addition of one or more of the following ingredients: honey, syrup, marshmallows, raisins, bananas, marshmallow fluff or dried fruit. A combination of any of these additions would be great.
In my opinion there are two really reasons why the PB&J is so popular. The first is it taste great and it contains no perishable ingredients so there is no need for refrigeration, great on a hot day while at school or on a picnic.
I was looking for a recipe to add to this post and came across this to share, Grilled Peanut Butter and Jelly.