It's interesting because this gets into the entire "Do you have a right to your own body?" debate.

Just a side note: just because things are natural/plants doesn't mean they won't kill you. There are a ton of poisonous mushrooms out there for instance.

But anyway, if you want to eat poisonous mushrooms, you should be able to right? Should you be able to kill yourself? Do you have a right to what happens to your body after you die? Who..owns your body?

There are a ton of great articles out there on all of those questions and they all get into really weird grey legal areas. Have phun.