The Midwest Fruit and Vegetable Book (Illinois Edition) by James A. Fizzell
This book is amazing! There are many types of vegetables listed with advice as when to plant them and any special notes for care. I am revising and reworking (hopefully to publish here soon) my planting calender based on the recommendations of this book.
Carrots Love Tomatoes by Louise Riotte
My only experience with companion gardening is planting tons of marigolds amongst your vegetables as my Grandpa had done. I had an exterminator comment that that was a wise idea but the actual benefits eluded me.
The New Victory Garden by Bob Thomson
This is an older book, but the pictures are fantastic. I haven't had time to take a good look, but I wanted to get some creative ideas to use in a small garden.
The Soul of Soil: A Soil-Building Guide for Master Gardeners and Farmers by Grace Gershuny
Also haven't really touched this book, but I am hoping it will guide me into drastically improving my backyard soil.