Have you tried Googling Native Ohio medicinal herbs? There are actually a few books written about different areas and their herbs. You might find some info. If not... there's a few that are everywhere, like Mullein, which I think grows everywhere in the US... stuff like that.... chickweed.... etc.

Congrats on becoming interested in herbs and honoring your grandmother. Check the Herb Society of America. They maintain a huge garden near Cleveland. Google them and then search for chapters near you. You can also check with your local county cooperative extension for members who are into herbs. Then, google "Ohio" and "herb clubs" or "herbal events" or "native herbs". Good luck!