Hello, it's me!
I am the King Cup (Caltha palustris).
Because spring came back, I also came back.
The King Cup likes to have wet feet. In swampy places on fertile soil it can appear in large amounts. Like here in an Alder wood where the branches of a small stream penetrate everywhere. The flowering is abundant while it lasts, only a few weeks.
Yes, it looks like a big buttercup. Both belong to the same family of Ranunculaceae.