Thanks carol, I think you may be right! Looks like I've got another fun one to remove...

Celandine poppies. They naturalize all over my shady areas and I LOVE them. They are cheery in spring. Maybe I'm into the natural look and love plants that grow without any effort from me and aren't bothered by any animals. The flowers on mine are big and so soft to the touch.

Check against Stylophorum also.

Leaves fit Stylophorum better. I consider it a great wildflower and not a weed,a weedy wildflower, because it self sows all over the place and will smother spring ephemerals if it gets near them. Deadhead or remove unwanted seedlings.Great if in the right spot though.

Now that I look, I think it's stylophorum - the leaves give it away. It's not unattractive but it has invaded some of my vegetable beds. I like it on my rocky slope, though.

I find it fairly difficult to tell the difference at this stage, though the seed pods look quite different. The page linked below might help. I have Chelidonium (which has the long seed pods) and am on constant watch for it in spring in the hopes of ripping it out before it goes to seed. There is quite a bit less now than there was when we moved in. Stylophorum is native and gently seeds around here. Chelidonium is a Eurasian import that is quite weedy.
Greater Celandine (Chelidonium majus) vs Celandine Poppy (Stylophorum diphyllum)

That is a great link, NHBabs! I will keep an eye out for the seed pods, but I'm pretty sure now that I see the leaves side by side that I have stylophorum. It can't stay in my vegetable beds but I'll let it prosper elsewhere! :)

The Chelidonium leaves are grouped in threes with two support leaves at nodes.The Stylophorum looks more like an oak leaf.