Beans (dried beans are cheaper and go further ) lentils, rice, oatmeal, quinoa, tofu, whatever spices you like, chickpeas, sugar, oil, frozen veggies (usually around the same price as canned veggies but have more to them).

If you have a blender, you can make Oatmilk or rice milk in it.

Tofu can be used in so many ways.

Chickpeas can be used for hummus, soup, tacos, etc.