I remember being in line in the cafeteria, and eating lunches, in my first elementary school (grades 1-3), but not any of the food I ate. I know we packed a lunch some days and bought the meal there other days, but I can only take an educated guess that my sack lunches consisted of a sandwich and probably bananas or apples or cookies.
The one solid memory from that school cafeteria is when we kids discovered those flavored straws that made the milk taste like chocolate or strawberry. Suddenly those were all the rage, and aside from whenever we'd drink chocolate milk at home, those were probably the times I most liked milk itself. Somehow or other, my sister and I both grew up not liking plain milk.
Fast forward to high school, the other really solid memory for lunches. They had a separate section of the cafeteria line, every day, for hamburgers and hot dogs, and I loved those hamburgers. They were simplicity itself -- all I remember is just the patty on a bun, and putting mustard or ketchup on them -- but to this day I can picture them and taste them. Later, in my senior year, the few kids who had cars would go up to a mom-and-pop place and bring back their hamburgers and fries, and those were really to die for. I'd give anything to have those back. Or to figure out how to recreate a simple thing like a patty on a bun. You can't, really. It's the blend of beef, the way they were cooked, etc.