Books I would recommend as worth your money are these:
Square Foot Gardening
by Mel Bartholomew
This was one of the first books gardening books I bought. Its a classic now. Mel Bartholomew makes it easy to start and grow a garden in limited space. This book is well illustrated and great for anyone just starting out gardening. His ideas can be applied in all sorts of scenarios. I enjoy referring back to his book even now for all of the charts, designs and illustrations.
Seed to Seed
by Suzanne Ashworth
This is a comprehensive guide on seed saving. If you have ever wanted to save your own seeds from year to year or be able to trade seeds with other, this is your book. Suzanne gives very detailed instructions for a large variety of plants. Pollination methods, seed procurement and storage are all covered here. Great reference book to have around.
Neil Sperry's Complete Guide To Texas Gardening
by Neil Sperry
I know this is a regional book for Texas, but Neil is a gardening expert here. His information is all research-based and reliable. He provides plant data that's vital for our area. We have some harsh conditions at times, so knowing what plants grow best is important.
** In your area look for books and references written by Extension services or those related to them. They have spent years testing plants and soil conditions to maximize production. Choosing poorly suited plants for your area sets you up for a difficult gardening experience.
How To Grow More Vegetables
Do you see the garden picture with onions in my previous post, that is from using this method. Maximizing food production is the purpose of this book. It takes you through charts and calculations to determine how much food you need to grow to provide for your family. It takes into consideration a full calorie diet. This book covers it all from seed starting to companion planting. I use it regularly.
Encyclopedia of Country Living
"The Original Manual for Living off the Land & Doing It Yourself" -- Plain and simple, its hard to know it all if you choose to move to the country and grow your own food. This book covers a wide variety of subjects that I would never be able to keep up with on my own. For me, growing plants is one thing, but keeping up with all of needs of my animals is another. This book is like having a good country neighbor who is willing to show you the ropes around your new homestead. At 900+ pages of information I think its a winner.
Having a strong reference base is key for me. I would be lost if I didn't have guides to show me what I need to do and when to do it. All of these books make for great reading also in the winter months when garden planning is crucial. There is no way of calculating how much time and money I have saved over the years because of them.