I believe Euell Gibbons was a proponent of eating poison ivy. I think it is in one of his books. A lecturer at the Ohio Agricultural Experiment Station (1958) suggested drinking the milk of goats grazing on poison ivy. Hey, if everyone knew these things, the drug companies would go bust. And that would be wonderful, imo.

Jewel weed is known as a preventive. It usually grows nearby and can simply be rubbed on skin after exposure to prevent or relieve effects.

Stinging nettles are monsters here in the NW. I was informed recently that a sword fern leaf rubbed on will alleviate the pain. I found just licking it, if reachable, or using spit if not, helps amazingly.