OK, so you haven't done a lot of cooking from scratch. I've found an amazing number of people even my age (almost 50) who have never gotten past convenience foods.
To make one thing clear, btw, my daughters are probably giggling at the idea of me writing about cooking. I don't particularly enjoy cooking (though I love baking), and when my oldest was about 2 and showed interest, I was thrilled to let her help. As she showed herself to be competent and safe, I let her make more and more. Years later, when I got divorced and had to work full time, she took over most of the cooking, and as a thank you, I paid for several gourmet-type classes for her (with the bonus that she then made some incredible stir-fries and other dishes). However, I do take credit for at least teaching her an attitude about cooking, which is to be willing to take chances, and the idea that very few recipes are cast in stone.
So here is a recipe that I invented, as in I just started putting things together. It's cheap, tasty, filling and nutritious, and you can change it infinitely. All it took was a general knowledge of cooking times and what goes well together and the basic idea for making soups and stews.
Start with about a quart of broth, possibly about a cup more if you don't want it too thick. Put it in a 2 qt sauce pan with a tight fitting lid, add a little salt, pepper, and a very little cayenne pepper, then heat to a low boil. Rinse and add an eighth to a quarter cup of dry pinto beans. Stir in, cover, reduce to a moderate simmer for about 10 minutes. Rinse and add a half cup of brown rice. Stir in, cover, cook at a moderate simmer for about 10 minutes. Rinse and add about a quarter cup of dry black beans. Stir in, cover, cook at a moderate simmer for about 10 minutes. Add about a quarter to a third cup of split peas and about a quarter cup of chopped onions (I buy frozen bags of pre-chopped onions that work perfectly for this). Stir in, cover, cook at a moderate simmer for about 20 minutes. At this point, test at least one grain of each ingredient to make sure they're soft. It may need 5 to 10 minutes more cooking time. Serve over a slice of whole wheat bread.
The only thing complicated about this recipe is that you have to keep coming back every 10 minutes to add something. You really need to stir and check to make sure it isn't boiling over anyway, but if you aren't too picky about something being a bit overcooked and your lid has a steam vent, add the brown rice at the beginning with the pintos and cook for 20 minutes, and then add the split peas and onions with the black beans and cook for 30 minutes for a total of about 50.
Made like this and served over whole wheat bread, I get enough for at least three hearty lunches (actually usually four, but I'm allowing for bigger appetites) at a cost for the entire pot of soup (based on my sales prices) of about $.45, plus the bread it's served with. That's either three lunches for about $.23 each (counting bread) or a meal for three for about $.70. It's a complete protein because you're combining legumes, brown rice, and whole wheat bread. And it's low fat to no fat, depending on the broth you use, and is even better warmed up as leftovers. That little touch of cayenne keeps it from being too bland without overdoing the salt.
Don't forget that you can change this around and substitute other legumes and grains. Just pay attention to which things take the longest to cook. It can also be "beefed" up a bit. Have a little leftover pork roast, ham, or bacon? They go great in this. I find a single slice of cooked pork loin, about 3 ounces, shredded into the pot when I add the onions and split peas, make this seem much more like a meal in itself. Garlic would probably go really well with this, and a little potato. Mushroom too, though mushrooms generally are getting out of the cheap food category. You can double or triple the batch or increase the broth to make it soupier. Don't reduce the amount of broth, though, because this is pretty thick at these proportions, especially the next day.