Quinoa and Brown Rice
You might be tempted to put the quinoa back on the shelf because it's not exactly the cheapest, but it's so worth keeping in your pantry because a little bit goes a really long way. One cup of uncooked quinoa will give you three or four meals, and that'll only put a small dent in the bag. Brown rice is a cheaper alternative that works just as well. I mix it with veggies, leftover chicken, or anything else I have for a filling lunch or dinner.