It looks a lot like Stylophorum diphyllum (woodland poppy or celandine poppy) Have the blooms increased in size at all since this photo was taken? The leaves look just like my woodland poppy, but usually the blooms aren't quite so... tiny lol
Thank you for your inputs! I agree definitely seems to be some kind of a buttercup/ranunculus ... I have been looking at pages of images. But so far the leaves are not the same, but there seems to be every shape imaginable among the species.