Well, I am sure Rodale has a basic gardening book that should provide plenty of good information. But I will recommend Square Foot Gardening, by Mel Bartholemew, as a great book to read when learning about gardening....all his information is organic, and he has some good charts and stuff listing different nutrient compositions of various organic amendments, but his square foot method is a specific style; that is, you can garden organically in a different way than the square foot method, but it is worth reading about his methods to see if this style suits you. I dont EXACTLY square foot garden, but i definitely use his principles and this information, and specifically his spacing recommendations and it was the most influential gardening book i have read.
good luck and happy gardening!