For cheap eating, I find that a few general good guidelines are to buy the vegetables that are cheap, and work with that, use dried beans (rather than canned), and eat beans/lentils/chickpeas and rice for protein a few nights a week, and use stew type dishes to stretch out small quantities of meat. Pasta, potatoes and rice are cheap - often cheaper than decent bread.
For specific recipes -
Taco rice, if you've got ground beef.
Cook up some onions and ground beef with taco seasonings (you can make your own from jarred spices). Make plain white rice, short grain by preference. Serve the meat on the rice, and top with shredded lettuce, chopped tomatoes, some grated cheese, and maybe a few tortilla chips.
This, by the way, is a genuine *Japanese* dish, popular in the Okinawan Islands.
Chickpeas are great for cheap protein. I buy the dried ones, and cook overnight in the slow cooker, and freeze in batches for quick use (saving the broth for soups). You can use them in a salad (with vegetables, lemon juice and olive oil with a bit of garlic), or make them into a stew or curry (saute onions and garlic and celery, add your cooked chickpeas, then cook with tomatoes and cumin, or with a spoonful of yoghurt and curry spices. Some chopped green leafy vegetables go well in either version (frozen spinach, kale etc), or even just toss in the leaves off of your celery.
Cabbage is usually cheap. You can do sour cabbage with caraway, 7 day coleslaw, creamed cabbage with noodles, etc. Carrots are cheap, and grated carrot salad is easy and tasty (grated carrots, lemon juice, a bit of olive oil). Or pureed carrot and ginger soup, or carrot and potato soup.
Pasta with spaghetti sauce, of course, and chili con carne (use dried beans to save money).
For cheap meat - stewed beef shanks (make a hearty stew with onion and carrots and celery and potatoes. Add mushrooms if you can get them from the cheap rack at the grocery store - they taste better when they start to look funny). Or a moroccan style beef and chickpea stew with tomatoes. Or go for chicken thighs (cheaper than white meat) and cook with onions, carrots, celery, canned tomatoes, etc.
Frozen vegetables can be a good option if the local produce isn't great yet, or is expensive - I find green beans, peas and corn particularly useful.
And eggs, as others have said - omelettes, fried eggs, poached eggs, baked eggs, savory Japanese egg custards.
If you can get a whole chicken on sale, you can get a lot of eating out of it. Roast it and serve it the first night (save the pan drippings!) Then carve off the leftover meat, and use it for the next night - in a pasta sauce, or salad. Cook up the carcass and pan drippings to give you stock, which give you soup on the third night. Save things like celery tops and bottoms, the ends of onions and carrots, and other veggie bits, and add them to the carcass to make a really flavourful stock.