Some people think witches used the plant belladonna. Lethal in large doses, in smaller doses it causes hallucinations, and especially in combination with other plants such as opium makes a flying ointment that makes you feel like you're floating through the air. Witches would use the ointment before flying on their brooms-traditional witch folklore holds that they would fly at night to their festivals/pagan sacrifices/Witches' Dances.
Also reminds me of reading about toad licking in association with "Frog Prince". Another way to get psychadelic visions, some people think this phenomenon could have led to the image of kissing a frog and seeing a handsome prince where none was before; however, the kissing scene of Frog Prince is only a recent phenomenon. But it still may account for the presence of frogs in fairy tales as transformative animals. By the way, be sure to check out The Case of the Missing Kiss over on Quill and qwerty if you haven't already-a very interesting and well-researched look into Frog Prince tales and the addition of the kiss, as opposed to throwing the slimy animal against a wall.
William Robert Symonds
This was going through my head the whole time I wrote this post...