maybe wood poppy?
compare to Stylophorum diphyllum

Here is a link that might be useful: Stylophorum diphylum images

I was thinking that but looks a little off. Could it be Chelidonium majus (Celandine)? If it is it's invasive here and I'll pull it. Looks like seed pod is the way to differentiate. I found an article here.

http://rivercitywildones.org/files/A_Tale_of_Two_Poppies.pdf

My little woods is primarily natives with a couple invasives that I have been working on eliminating. Every year I seem to find a couple new species and it's a pretty small woods.

This specimen is surrounded by trout liliy, bloodroot, a lady slipper, Jack-in-the-pulpit, maidenhead and ostrich fern, pasque flower and wood anemone.

leaves are tricky, between the two. easier to tell by the flowers.the easiest way to tell is the seed pod. the link below has some photos that compare them.

ETA - sounds like your "little woods" look like a "little bit-o heaven" ; )
keep on doin' what you're doin'

Here is a link that might be useful: wildlifegardeners - Stylophorum vs Chelidonium

This post was edited by bubbleoffplumb on Thu, May 15, 14 at 21:52

Thanks! I'll just keep an eye on it and deal with it when it goes to pod. There is only the one so it'll be easy to control. I'm finally getting the mustard garlic and buckthorn under control as well.