It is listed as native to the northeast and some central states. That would include Virginia and Maryland The "point of origin" appears to be western Pennsylvania or at least that's where the first recordings of it have been listed from. Canada is the extreme edge of its northern survivability. Southern Virginia seems to be the southern limit for good growth. It can be ephemeral in Maryland and Virginia summer heat.

It is often confused with its relative Chelidonium majus, which is from Eurasia (which I've seen sold as wood poppy). The main difference is the size of the flowers 3/4 inch vs. 1-2 inches for Stylophorum diphyllum

Thanks, Kim. I couldn't find it in the Native Maryland plants, but I'm pretty sure that's what I have. A librarian showed me a pic of the chelidonium majus but I have a very different leaf, not round but very distinct lobes and veins.