It is believed that ergot poisoning, also known as Saint Anthony's Fire, may have played a role in outbreaks of witchcraft during colonial times in New England, most notably the Salem Witch trials. Saint Anthony's Fire, named for the patron saint of fire, has symptoms that include a burning sensation in the hands and feet, hallucinations, and gangrene in the extremities (most notably the nose and ears). Women who were tried as witches during the 1690s, and the children who appeared to be possessed by these witches, could have ingested stale rye bread upon which the ergot fungus has grown and then appeared to be possessed by the devil.
It was also from this fungus that Albert Hofmann first extracted LSD in 1938.