Hoffman was creating some kind of psychotropic drug, and his drop accidentally fell on the wound on his arm, and after that he went home, seeing very strange images. This is how the LSD effect was discovered.
LSD-25, DLK-25 (Lysergsäurediethylamid - d-lysergic acid diethylamide). It was first synthesized by Albert Hoffmann in 1938. LSD is obtained by attaching a diethylamide group to lysergic acid, which in turn is obtained from ergot, a marsupial fungus that parasitizes cereals.
DLK-25 is really difficult to synthesize, but this has little effect on the breadth of distribution of this substance. In Russia, you can also buy LSD-25 of good quality, confirmed by the results of mass spectrometry, for about 2000 rubles / 200 μg.
LSD is lezirgic acid diethylamide. It was originally synthesized from ergot - if memory serves - a fungus on rye, which fell into the hands of Albert Hoffmann, who rode a bicycle across the field. You can read more in his autobiographical book "LSD - My Problem Child"