Not every character is running around a world with convenient chemically created pills and drug stores on every corner. Before popping pills became common, and even now in many fantasy worlds, the best medicine for whatever may ail you came from the forests and fields. Here are some common herbs used in literature and real life. This list is for reference purposes only.

Chamomile – The flower heads can be used to help relieve indigestion, colic, anxiety, and skin inflammations.

Feverfew – The flowers and leaves of this plant can help with headaches and migraines, arthritis, and some skin conditions. Has also been used to treat tooth aches, insect bites, stomach aches and more.

Sage – This plant can be used to help with mouth and throat inflammations.

Comfrey – Treats bruises and sprains.

Yarrow – Helps reduce inflammation.

Barberry – Used to treat scurvy, skin and gastro-intestinal ailments.

Bilberry – This plant has been used at various times to prevent night blindness, treat stomach cramps, diabetes, and diarrhea, as well as varicose veins, hemorrhoids, and bruising.

Burdock – Used to treat liver problems, urinary tract infections, ulcers, eczema, to boost energy, and to boost the immune system.

Catnip – This herb isn’t just used to make cats tweak out, but also for coughs, bruises, restlessness, upset stomach, colic, colds, fever allergies, and sometimes as a mild sedative (at least for people).

For a more complete list check out these links:

wikipedia

Herbs List