Example; Ginseng for fibromyalgia, Kava Kava for tension headaches and neuropathic pain, St. John's Wort for sciatica, arthritis, and neuropathic pain, Valerian root for spasms and muscle cramps, Clove for toothaches.
Some people use cannabis oil or smoke it. Like modern medicine, medicinal plants carry the same warnings and generally shouldn't be mixed with modern medicine unless proven to co-exist, many many good books out their on this subject. Keep in mind medicinal plants not only can cause harm but also kill.
Some local plants we use on the West coast can be deadly on the East coast so be extremely cautious when seeking natural medicinal plants on the internet and don't trust posted pictures.