Pasta and sauce. As long as you have a few basic herbs and spices on hand (garlic powder, Italian seasonings, salt pepper), you can buy a can of crushed tomatoes, and a box of pasta, and you can have several delicious, filling meals for less than 5 bucks total. Spend a little more and toss in ground beef, ground pork, or mushrooms, or a combination of all three.

Aldi has the ingredients for really cheap. You can even buy a pound of ground pork for only about $3. The spices are only about a buck each.