If you want to go for a double whammy, I would recommend the book, In Defense of Food, as a companion. Together they may change the way you think about the food you eat.
It's funny that Time came out with an article in the Aug. 31st '09 issue titled, "The Real Cost of Cheap Food," which details some of the issues brought up in the book. I recommend the article, too, while you're at it. (The link will only take you to a picture of the cover, because at the writing of this post, this is the current issue of the magazine and so the article isn't available online yet).
So read, and then go to your local farmers market, or begin planning your garden for next year.