Thanks for sharing your story. I live in Korea where a lot of wild herbs are harvested, sometimes even cultivated, and used for food and/or medicine.
I had something similar happen to me with the lacquer tree. It is used here in various ways. The first way I ever had it was in soup. The wood is harvested and dried, then boiled in a soup stock. I was told to be cautious as some people are allergic, but I had no reaction. So later, when I came across a lacquer tree, I was bold enough to try the young leaves in a pancake, which is one of the ways it is eaten here. Luckily, I had done a little more research and was aware of the plant's similarity to poison ivy, which I had been highly allergic to as a child. So I only had one pancake. But that was enough to set off an allergic reaction that left me with itchy rashes on various parts of my body for several days.
Mugwort is also very common in Korea and I have eaten it steamed in rice cakes. I was fine but maybe the steaming changed its properties. Or maybe it wasn't as much as you ate, or maybe I'm just not as sensitive to that particular plant. (As a side note, it works very well as a mosquito repellent when dried and then burned. The smoke smells aromatic to me but mosquitoes don't like it.
I hope your story doesn't discourage people from trying wild herbs, but rather serves as a prudent warning to exercise caution, especially when trying a new plant for the first time - or when trying the same plant from a different geographical area, or prepared in a different way.