Baked potato with beans - Tin of beans 30p each and a bag of baked potatoes is £1.50ish.
Lentil Dahl: red lentils (£2) onions (£1/2), garlic, stock, tin of tomatoes (30p), whatever spices you want/have in (I like tumeric and cumin and curry powder but whatever you have), serve with rice (85p).
Green lentils curry - couple tins of green lentils, onion, garlic, any curry paste, stock, tin of tomatoes, any frozen green veg (we like spinach). Serve with rice. I also add cubes of potatoes and let it simmer for ages until they are cooked, if you can spare a potato.
Butterbean stew - a couple tins of butterbeans, red peppers, garlic, onions, tinned tomatoes, any herbs you want, frozen spinach again, bung in the oven and serve with rice or bread.
You can make these with a bag of onions for a couple pounds, garlic bulb for £1, a few tins of tomatoes which are 30p each, pack of stock cubes for £1, bag of frozen spinach for £1.50, red pepper for 65p, beans for 30p each, bag of baked potatoes for £1.50. And a few pounds for the other bits.
Serve whatever steamed veg you have on the side.