You've already received some great advice. It seems to me that if you veer away from convenience foods, stock up on staples when those items are on sale (canned tomatoes, pasta sauces, frozen veggies, etc...), buy seasonal produce which tends to be cheaper, shop the bulk bins as opposed to pre-packaged items (only paying for the cost of packaging most of the time like with oatmeal, rice, flours, etc...), and try to split the costs of large items (like purchased from Costco or BJ's) with a roommate if you've got one, that will save you quite a bit.
Peanut butter is a great food. Smear it on toast for breakfast, make sandwiches with it for lunch, use it to dip apple slices in for a snack, have it with whole wheat crackers for a snack, etc...
Eggs were mentioned and they are cheap and great source of protein! Eat them for breakfast (fried, scrambled, omelettes), lunch (boiled, egg salad, in a tortilla with beans, salsa), dinner (quiche, strata, fried egg sandwich, french toast). Plus, they're quick and typically college students don't have much time.
Rotissere chickens. Pound for pound, if you can buy them on sale, it's cheaper than buying and preparing a fryer yourself. Our local grocery store marks down the leftover rotissere chickens after 8pm, so that is a great time to buy. We're a family of 3 and one lasts us about 2-3 days depending on size. So, you can really get a lot of of one and you can also prepare casseroles or soup with it and freeze it so no fear of having it go to waste. Great for sandwiches, on top of salads, in casseroles, soups.
Baked potatoes. Cheap, portable. Also, cottage potatoes, homemade french fries (the seasoning possibilities are endless), mashed, potato soup, etc...
Cottage cheese. Great source of protein. Pair it with fruit for breakfast. Plunk it on top of a salad for lunch or dinner. Mix it in with your spaghetti sauce for a protein boost at dinner.
Beans. Learn how to prepare them from dried. It is very simple, just requires some planning ahead for the soaking. Then, pair them with brown rice and some salsa for a mexican bowl. Put in a tortilla for a burrito. On top of tortilla chips for nachos.
Finally, whenever you get invited to dinner, say "yes."
And, attend all free social events that provide food. Hey, desperate times call for desperate measures.