Frugal, not sexy and available everywhere. Dry beans being the cheapest and available organic for like, 79cents a pound.
Try a veggie chili or fantastic omelette for dinner. Spaghetti is a fav cheap standby as is lentil soup.
Also having fun with miso soup, oriental noodle soups, stir frys. A grilled tomato sandwich or grill cheese.
Vegetable soup, bean soup, ANY kind of soup (soup is great frugal).
Oatmeal or other grain cereal. Granola (OK, its not cheap but a little bit is very filling).