I have the same plant and I think I got it at the swap, too. It reminds me a lot of wood poppy, but the flowers are smaller and it is about 5" taller. It DOES self seed like crazy. I've wondered if it isn't a wild version of wood poppy.
Anyone????
darcieg

darcie2--I tried to email you about the swap, but you don't have your email turned on on your page. If you click on my name ellen_n, you can send me an email that I can reply to.

This is off topic, but I thought the message would get lost in the swap thread.

Ellen

Mine look like this and I think they are wood poppies.

darcie--based on gardengranma's response, I think I know what plant you are talking about. It is a close relative of wood poppy (celandine poppy). I'll let you know if I come across the name.

I realize I can do a better job of describing my plant. The heart-shaped leaves all come from a single point in the clump and the flower stalk comes up from the same point. Each stalk has a number of yellow daisy-like flowers on it. I guess I'll keep searching for images.

Aha! I found it. It's golden ragwort. Packera aurea (Senecio aureus). (see the link) I'll add it to my swap list.

Maybe I'll find the wood poppy cousin.

Here is a link that might be useful: Golden Ragwort

Nope, that's not it. I have Golden Ragwort and love it. This has leaves that go much higher up on the plant and the flowers are fuller.
Darcie

I mean the Golden Ragwort is the plant I have that I was trying to identify. I think I also have the plant that you are trying to identify, but I haven't found the name of that yet. I know I saw it in a book once before.

I think it may be superbus.....I think I may have started this at the swap I had numerous of these at my old Mt. Pleasant house and loved them....

http://www.estabrooksonline.com/catalog2/perennials/perennial.asp?id=Trollius