

https://en.wikipedia.org/wiki/List_of_herbs_with_known_adverse_effects
The list itself says it is incomplete and I immediately thought of a couple items not listed that have known toxicity issues:
https://en.wikipedia.org/wiki/Perilla_frutescens#Traditional_medicine,_phytochemicals,_and_toxicity
This surely varies by state, but in Alaska, for example, I’m told Japanese vacationers LOVE to try out guns. So, if you can rent a gun on a range, shooting off weapons is the most American thing I can think to do before you leave.