I know this is a super old thread
but I was hoping to revive it. My family and I try to eat "locavore" and seasonally as much as possible. This website has always helped me: http://www.fieldtoplate.com/guide.php
(Sorry, it's a US-centric resource). It has links to sites specific to most states, and several larger regions of the US regarding what is in season.
My primary cookbook for my family is "The Little House Cookbook", based on the Little House on the Prairie books. It isn't specifically local/in-season, but it is a great resource for cooking with vegetables that grow well in the midwest USA, and using wild game.
One thing I am always wondering about is the ability to get certain staples locally. I don't know of anyone who produces their own sugar or flour or rice, or other staples like that, locally; as of now, I continue to buy things like this from the store, but it still irks me. Am I just not looking in the right place? If anyone has any suggestions, I am all ears. I have tried going to the local Amish communities, but I found out that they purchase huge quantities of staples from other places in the country, have it shipped to them, and then sell it repackaged; so not as local as I was hoping.