I received this in a plant trade with this name. Now I am told it is not H. 'Summer Sun'. Sorry the photo isn't more clear.
SOLVED: Heliopsis 'Summer Sun'?
It is kind of hard to tell from the picture. Yours does seem to be wispier than mine but the flower looks right. If I think about it, I will post mine tomorrow. I may have also put it in the plant data base.
I think the leaves are different than heliopsis. It looks like Rudbeckia lanciniata to me. 'Goldquelle' is a compact double flowered variety. I had 'Golden Glow' for a while which gets about 8 feet tall. It always flopped when it bloomed so I decided to get rid of it.
if it's Rudbeckia lanciniata get it out now. This is the most invasive plant I've ever seen. I let it go for a couple of years, having bought it as something else. Now I can't get rid of it, it spreads from every little piece of root.