Main categories of hallucinogens:
1.) Related to serotonin (DMT, LSD, psilcybin (mushrooms) and mescaline)
2.) Related to norepinephrine (Ecstasy, nutmeg)
3.) Related to acetylcholine (Mandrake)
4.) Glutamate hallucinogenic, including dissociative anesthetics (Ketamine, PCP)