I don't think anybody recognizes from this blurry pic. Can you add another one? Compare to Ranculcus though.

The picture is quite blurry, but... I almost think it's Vinca?

If so, I'm terribly sorry, it's one tough plant to get rid of.

If it's vinca, just pull up the stems and keep pulling. Then repeat as soon as you see more. You'll probably need to dig some of the older places.

Then when you think you've gotten it all, you still need to keep an eye out for it to grow back from some bits you missed.

Here's what vinca looks like:
http://www.missouribotanicalgarden.org/PlantFinder/FullImageDisplay.aspx?documentid=3880

Herbicides don't work well on vinca because of the waxy coating on its leaves and stems.

Pretty positive it's not Vinca. Can we have an in focus picture? It could be lots of things as it is.