I'm not in school, but at my highschool I would always get a cheese burger or chicken burger and whatever else they served with it, or I would get some of their fries. My Freshman year they had the best fries X3 But they took them away my Sophomore year. They were apparently 'unhealthy'.
At the college where I got my GED I would always get a bag of popcorn and occasionally a bagel. Popcorn was free, so I always got a bag while my class was in break time.
When I was in grade school I always got a hot lunch.