Let me introduce you to the King of Simple: Mark Bittman.
Mark Bittman - The New York Times
The Minimalist - Italian Escarole Soup With Creamy Rice and Aromatic Garlic - NYTimes.com
One thing I love about his recipes is that once you have confidence in your cooking, you can swap things in or out as you see fit; ultimately, it's more about the method.
Hit up your public library and look for this cookbook:
You don't want to buy it because you won't need it very long, but if you'd like to increase your competence in method it's great. Method is important because once you know how to saute, broil, roast, etc. you open up endless possibilities. Also, learn to stir-fry. Stir-frying up a bunch of veggies in light oil is relatively easy and a quick way to get some veg on the table.
One dish we eat a lot is just beans (usually black), rice (brown, long or short grain), some cheese, salsa, and sour cream. I make the beans from dried. It is a lot cheaper because we buy our beans and rice in bulk. It isn't hard to make beans from dried, and to be honest, it doesn't even require forethought. Mark Bittman's
How to Cook Everything Vegetarian has a couple methods for cooking beans if you've forgotten to soak them, or suddenly decide that afternoon that you want beans. Always make more than you need for that meal. Put the extra in a freeze-proof container, making sure the beans are covered by the bean juice, leaving sufficient head space in the container, and you can freeze the beans until you're ready to make a dish that needs some beans. Beans that have been frozen soften up a bit, so they're best in things like refried beans or a soup where you want them to fall apart a bit. And make extra rice too--throw the excess in a container in the fridge and use it the next day to make veggie fried rice.
What makes recipes easy are skills--once you have them, you're good to go. Some good vegetarian cookbooks to check out, because veg meals are cheap: the abovementioned
How to Cook Everything Vegetarian and
The Moosewood Cookbook (the original one, look for it at the library as it's hard to find a copy of it). Online, I use
Apartment Therapy The Kitchn as a resource a lot. Just this week they had:
10 Tasty Dinners To Serve On The Cheap | Apartment Therapy The Kitchn