European indigenous psychoactives were primarily deliriant nightshades and amanita muscaria mushrooms - both of which are very interesting to read about but I've never felt compelled to try.
Taking nightshades and "speaking with the devil" seems entirely plausible to what people of that cultural mindset would have experienced. Erowid's Datura experience vault has a collection of first hand accounts of the experience, and they sound quite terrifying: being in a dream-like state for days at a time with heavy amnesia, hallucinations of people who aren't really there, dark ominous imagery and out of body experiences. Much more realistic hallucinations than are reported from psilocybes. See also "flying ointment" for some interesting (nsfw) context to 'witches riding brooms".
Everything I've read about the amanita muscaria experience makes me never want to experience it... thankfully we have a fair set of varied experiences with other mushroom varieties and many synthetic tryptamines with more pleasant experience and risk profiles.
Taking nightshades and "speaking with the devil" seems entirely plausible to what people of that cultural mindset would have experienced. Erowid's Datura experience vault has a collection of first hand accounts of the experience, and they sound quite terrifying: being in a dream-like state for days at a time with heavy amnesia, hallucinations of people who aren't really there, dark ominous imagery and out of body experiences. Much more realistic hallucinations than are reported from psilocybes. See also "flying ointment" for some interesting (nsfw) context to 'witches riding brooms".