"LSD (d-lysergic acid diethylamide) is one of the most potent mood-changing chemicals. It was discovered in 1938 and is manufactured from lysergic acid, which is found in ergot, a fungus that grows on rye and other grains."

Source

NIDA InfoFacts, "Hallucinogens: LSD, Peyote, Psilocybin, and PCP," National Institute on Drug Abuse (Bethesda, MD: National Institutes of Health, June 2009).