If you haven't grown food with your kids yet, NOW is the time to start! The best way to start is to let your child pick what he wants to grow. Let him do the research, or help him do it (it's nice when they learn a cell phone is good for research, too!) A lot of things can be grown in a pot. The easiest thing for me has been herbs and a lettuce table. Lettuce grows quickly, and herbs can be used regularly to add different flavors to dinner. I even use herbs for my smoothies sometimes, and they can definitely be tossed in to salads as well. If your child picks something that can take all summer to grow (like watermelon) I would start some lettuce or herbs that you can grow while you wait to harvest your watermelon.
Learning to grow food is more important now than ever before. We are NOT food secure. I don't want to elaborate on this, but we just simply need to be more self-sustaining than we currently are. It is a great idea to add gardening to your homeschool curriculum. There are so many things that kids can learn through gardening, like building planter boxes, how to keep soil healthy, composting, water storage, saving seeds, and even canning. It's science, history, math, reading, and exercise!
I forgot to mention, playing in the dirt is also healthy. It helps with grounding, and your kids are also getting fresh air and sunshine. As that sneaker company says, JUST DO IT!