My approach then was to learn about herbs and then source them from suppliers. For my SCA Forestry project, I am going to focus, at this time, on local plants that I can see growing in the wild, learning to identify and then discover the uses (both modern and historic) if I do not already know them.
One thing that always has fascinated me in the SCA is learning about things I find to be utterly common (such as the poison ivy mentioned earlier in this blog or common, and deeply loved, foods like potatoes) would have been unheard of for my persona in period. So a large part of this, for me, will involve comparing my world to that of my 14th Century Forester persona's.
I will note that I am overly cautious about plants that I did not deliberately grow myself. When I am identifying a plant, I make use of several books that I already own (and have ordered a few more) and a number of websites to make absolutely sure that what I think I have is what I actually have. I never check with less than 5 sources and prefer those that point out very clear identifiers to help confirm a plant. I also look to see if there are look-a-likes that are harmful and triple check to make sure I didn't stumble on that weed instead.
Safety has to come first.
I am fortunate that I have very few allergies to contend with in this field. This makes wild edibles a somewhat safe game for me. If you are unfortunately enough to have a number of plant allergies (or drug allergies), I highly recommend that you learn what wild plants might be related to those items before testing anything yourself.
And safety is even more important when talking about herbal remedies. There is more to it than knowing about whether a plant is poison or not (or in what quantities it becomes harmful). Herbal medicines can interact with your modern drugs (or each other) in negative ways, and can create harmful side effects or lessen the functionality of your prescribed medication. If you have drug allergies, you need to verify that a plant does not have the same or similar components to those things you cannot take. I have a great personal example of this in that I am allergic to NSAIDS. All of them. They crash out my kidney function if I take even the smallest dose of the least of them (baby aspirin). I would be rich if I had $10 for every time I said "I cannot take NSAIDS" and some utter idiot (yes, I said it) recommended White Willow to me for arthritis.
Don't listen to the idiots on the internet about these things. Do your research, triple check everything, and take care when consuming wild plants or herbal medicines. I am going to get off my soapbox now and go back to figuring out what is growing in my yard.