If you live in a location with a reasonably warm climate, there is one thing to grow that I cannot recommend highly enough. Sweet potato. It is a nutritious, versatile vegetable that will grow with the minimum of fuss. There is a heap of information here.
I have had them growing for a couple of years and there are almost always some available to harvest. This is my latest haul.
Sweet potato can be boiled, baked, steamed and mashed. You can make chips or soup. I grate it coarsely and stir-fry it and serve instead of rice or pasta with chicken stir-fry or bolognaise sauce. You can even use it to make chocolate brownies.