San Pedro is a Peruvian cactus that grows high in the Andes and has been used in folk medicine by the native people and has been consumed in large quantities by humans so if you have the right species you could probably eat it without killing yourself. I remember my Spanish professor at Junior College She was from Peru, and live in Lima.
So much I learned about South American Culture from her. She told me when she would go to high elevations in the Andes they would take coca leave and make tea which would keep them from losing consciousness at the altitudes. So San Pedro has been was an importand ingredient in some South American hallucinogenic drinks like "cimora".