Here are some least expensive foods that are also nutritious:

Rice: Rice is very cheap, especially when bought in bulk.

Beans: Beans are very affordable and versatile, making them a great option for large meals.

Pasta: Pasta can be used in a variety of dishes and can be quite filling.

Lentils: Lentils are cheap, nutritious, and can be used in soups, stews, and salads.

Potatoes: Potatoes are versatile and filling. They can be prepared in numerous ways.

Cabbage: Cabbage can be used in salads, soups, and stews, and it goes a long way.

Oats: Oats are cheap and can be used in a variety of ways.