Herbs for Common Ailments by Anne McIntyre
Opinion: General, useful, recommended
This book is a very good tool for someone who doesn't know much about herbal remedies because it starts out exploring the vocabulary of the subject in depth. Then it explores the forms of remedies and there is a very useful chart listing what parts of what plant is good for what ailment. After that there is a short section on nutrition. What comes next is a section on each system of the body and various ailments that are associated with each and what type of herbs are used against each. This is really an excellent book. If you are just getting started you could easily start just with this one book. And if you are an experienced practitioner this would be a good reference book.

The Herbal Handbook: A User's Guide to Medical Herbalism by David Hoffman
Opinion: In-depth, useful, recommended
This book splits herbs into their functions, and then lists the herbs by ailment and contains directions for treatments. This is a very useful book to consult when you know what's wrong and you want to know how to cure it.

Gypsy Folk Medicine by Wanja von Hausen
Opinion: Useful, specific, recommended
This book gets into gypsy philosophy on healing and illness, but the useful part in my opinion are the recipes. This book has a lot of them and it also includes a section on remedies for animals.