Buttercups are a large genus of flowering plants called Ranunculus. It has yellow, shiny, petals, and grows wild in many places.
It is poisonous to eat for humans and cattle, but when dry the poison is not active.
Some other plants and people are named buttercup, based on the name of the yellow wildflower.
These include a type of pumpkin and the girl’s name Buttercup. (source)
Can guinea pigs eat buttercups?
Yes, they can without an issue. Just make sure that they haven’t been sprayed with pesticides.
For more foods that guinea pigs can and can’t eat, check out our guinea pig food list.