When I am on campus I eat a lot of fruit n nut granola bars, bananas, apples, or mini bags of salted nuts because they're cheap (or free at the student pantry) and easy to carry around.
When I have more money I'll buy tubs of hummus, guacamole or tofu spread and and eat with chips, crackers or bread. I actually consider this a real treat, because I'll get Hope flavored hummus (mostly Kale Pesto or Buffalo Bleu), mock tofu "egg salad," or guac with either a fresh local bread or real Mexican tortilla chips. Occasionally this is my lunch, with a piece of fruit.
When I crave chocolate I'll get a big fancy candy bar like Endangered Species.
At home I might make more complicated things, like smoothies in the summer, or toasted bread with various toppings in cooler weather.