LSD (lysergic acid diethylamide) is one of the major drugs making up the hallucinogen class. LSD was discovered in 1938 and is one of the most potent mood-changing chemicals. It is manufactured from lysergic acid, which is found in ergot, a fungus that grows on rye and other grains. LSD, commonly referred to as âacid,â is sold on the street in tablets, capsules, and, occasionally, liquid form.