Is this a Buttercup tree?

Oh, thank you, granny'sbuttons! The first thing I thought of was peony but I had to do some googling to check.

My yellow tree peony has leaves just like yours!

I've had a close look and consulted my little book and I think it is a hybrid of a perennial and tree peony.

Too big for Kerria Japonica. I would have said tree peony

The leaves don't quite look right for a peony. We have a peony in our garden. Not sure what it might be though.

I've had a look online and the flowers seem to match the Kerria Japonica Golden Guinnea but I'm not sure about the leaves.

Yes a tree peony, beautiful.

Yes I would say a tree peony too.

Looks like a yellow tree peony to me.