It depends on what you are specifically looking for. I have some great women's herbals. My favorite is the first one but they are all good...
Herbal Healing for women by Rosemary Gladstar
Herbal Remedies for Women by Amanda McQuade Crawford
The Complete women's Herbal by Anne McIntyre
for learning about 7 tonic herbs (in depth but fun)
Healing Wise by Susun Weed
for improving your health through what you eat as well as preventing and then if need be dealing with cancer (any cancer in my opinion, not just breast)
Breast Cancer, Breast Health by Susun Weed (all her books are wonderful)
for cleansing your body
14 Day Herbal Cleanse by Laurel Vukovic (lots of great ideas on little things you can do to increase your health)
Are you looking for anything else? I would recommend going to your local library and taking it everything herbal that looks interesting to you and then deciding what most suits your needs.

Sheri