I'm baffled- the leaves make me think vinca (periwinkle) but the flowers look more like a jasmine, which makes no sense in your neck of the woods. are the blooms fragrant at all?

Chinacat - I have such a poor sense of smell that if they have aroma, I would probably miss it.

The photo I posted is poor quality - the leaves are actually have jagged edges, not smooth edges like periwinkle. It's growing in shaded woodland.

It looks like pipsissewa (Chimaphila maculata), also called striped or spotted wintergreen. It's a lovely native. I've never seen enough of it on one place to think of it as a groundcover, but it does form small, loose clumps.

Thanks, mudmom - that's it! And I too have only a little patch of it - I guess it's not likely to be a groundcover.