Thanks for the additional information about Lesser Celandine (Ficaria verna) @Singa
I find it quite natural that the plant used this way. I've seen something about it in my flower books.
This plant should not be confused with Greater Celandine or Svalewort (Chelidonium majus). This plant is also toxic.
Among other things, they have fewer petals, and the leaves are entirely different.
They also belong to different plant families.
Yes, with plants you need to be extremely careful.
You can easily confuse them :-)
They have leaves and root system are very different.