My son after playing in the yard

Began crying incessantly that his hands itched and burned. This is the second time this has happened, and both were in diffferent yards. There isn't a rash when this happens, but whatever it is is really painful until I get enough anti itch cream on it. Any idea what he's touching? I'm assuming a plant of some kind, but like I said never a rash so wasn't thinking it was poison ivy or oak.