Check out sproutrobot.com. You enter your zipcode and it tells you when to plant what, and how to do it. And its free.
If you want to spend money, you can subscribe and they will send you the seeds.
Gardening together is a great homeschool project. You learn about germination, growing, food chains, food pyramid, harvesting, preparing, preserving and you get to EAT it!!
I learned about sproutrobot.com from freelyeducate.com