Psychedelics are potent psychoactive chemicals or plants that can alter perception, mood, and cognitive processes. Some of the most common psychedelics include: Psilocybin (found in certain mushrooms) LSD MDMA DMT (dimethyltryptamine) Ayahuasca (a brew containing a woody vine and the leaves of the chacruna plant) Mescaline (found in San Pedro and peyote cacti) Mind-altering psychedelic plants naturally grow as far afield as the Amazon, the Himalayas, and the Pacific Northwest of the US.