I'm sure pretty much everyone has RPed a healer, medic, doctor, shaman, etc. at some point. You can get by with having almost no knowledge about herbs, but for those looking to be a bit more specific, this is the place for you! These are some commonly used herbs and their uses, feel free to add some in the comments.
Borage-Flower and leaves are used for fever and cough(sweet)
Yarrow-Releives fevers and shortens colds and flu. Used topically it helps rash and itching(sweet, bitter aftertaste)
Comfrey-Roots are poisonous. Applied to the skin it can help wounds, joint inflammation, bruises, arthritis and fractures. Its tea can help upset stomachs and coughs(sweet)
Echinacea-Can be used for flu, headaches and cold
Juniper-Helps with upset stomach and upset stomach. It can help wounds, joint pain and muscle pain, and numb pain ***The berry is very bitter and can be harmful when eaten too often***
Chervil-Cough(sweet)
Tansy-Headache, joint pain, improves appetite, calms nerves,itching, bruises, sores, sprains, and swelling(bitter)
Thyme-Cough and possibly sore throat(pungent)
Watermint-Burns(bitter taste)
Yew-Stomachache, hiccups, (bitter)
This link might help with any questions or the uses of other herbs.
http://herbpathy.com/Glossary-meaning-of-bind-hid-d