I remember, as a child, holding buttercups under each other’s chins to see if the other person liked butter. The chin is supposed to glow yellow if the other likes butter.
All parts of buttercup are toxic, when raw. It is believed that heat destroys the toxin, so, traditionally, in medicine, all parts of the plant are first boiled.
Historically, Buttercup has been used for arrow and gunshot wounds, abscesses, sore throats, epilepsy, blood diseases, sore eyes, stomach issues, stiff muscles, snake bite, toothaches, as an emetic to counter poisons, to dry up smallpox sores, to stop nosebleeds, syphilis, asthma, rheumatism, pneumonia, warts, gout, neuralgia and more.
Definitely quite a useful herb, if used with knowledge and care.
It’s not meant to be complicated to be well, nor is it meant to be expensive.