(smart food choices for less --specific and general suggestions)
frozen pierogies --many servings for very little money!
pasta (plain or packaged --ex. Lipton or Pasta Roni) (recipe)
rice (side dish or main meal when other items added to it, such as stir fry)
soups (can be a hearty meal for very little -- 1 can can serve two for $1)
bulk food aisle items instead of prepackaged
homemade fruit roll-ups instead of store bought ones (recipe)
homemade pizza instead of frozen or ordered (recipe)
Bear Creek Minestrone soup mix (dry mix, makes 8 cups about $3 total)
Less choice cuts of meat are often priced much less. Sometimes they're tough, but tenderizing and marinating the meat will give you a decent meal for less.
Lean or extra-lean ground beef costs more. Buy the regular and after browning you can either drain off most of the fat and then place it on paper towels to absorb more, or rinse it under water (place it on a paper towl and carefully run under water), then pat dry and return to pan to continue your recipe.
Chicken breast often costs more when it's boned and skinless. Instead, try more cost efficient parts like thighs, drumsticks and split breast with skin (just remove the skin before cooking).
Avoid convenience foods! Yes, they're handy, but you pay for that convenience. Instead of buying precooked and cut chicken strips, cut and cook a bunch and bag it in the freezer to pull out when needed. Make your own frozen entrees and put them in resealable containers in the freezer. You can buy lettuce and romaine much cheaper and wash and cut it yourself (although quite often those handy salad in a bag things go on great specials).
One bag of pasta is only a couple of dollars and can provide many many servings worth of meals. Same goes for a box of rice. Try adding different sauces, soups, meats, veggies and whatever else you can think of to make different budget friendly meals.