That topic is called ethnobotany

Resin

Hate to disappoint you in your venture, but I believe that you'll find that most of the pharmaceutical preparations currently on the market are much,much more effective than any natural product. The branch of science that you'er seeking is termed PHARMACOGNOSY.Many pharmaceutical companies spend millions of dollars in the investigation of plant or animal products which exhibit physiological activity.

Also check under herbalism, especially if you are looking to grow, harvest, and/or make herbal formulas of some kind. There are alot of different schools of thought and materia medicas when it comes to herbalism and you can probably find one that suits your needs.

FataMorgana

A book i have would be right up your alley. He has tried or knew someone else that tried a multitude of medicinal plants. The very descriptive text will have you rolling in the aisles or shaking in horror. Good description of plants, uses and history. Just use comman sense.

Book is "AMERICAN MEDICINAL PLANTS" by Charles E Millspaugh First published in 1892 by John C Yorston & co. My edition was published in 1974 by Dover Publications INC, NY,NY My book is not for sale at any price. I injoy reading it too much.