Salvia is a popular garden plant. You can buy it in those 6-paks of young plants. So, if I see my wild neighbors in my garden smoking my plants, I'll know what is happening.

If they are saying Sage is hallucinogenic, it grows wild all over the place. The burning of Sage like incense has been a tradition for for many Native American tribes. The use of Red Willow Bark is also used, and it contains the equivalent of aspirin. That is a main ingredient in "peace pipe" smoking.