Yes, there are certainly many Hypericums native to N America but there are others which are not. H perforatum, which the one in the photo could well be, is an invasive alien in the US. Here is a link that might be useful: H perforatum

I agree that it's a coreopsis, probably a garden escapee.

Leaves look right for r. nudiflora. Wise to be cautious. Bill Welch warns they're "nothing more than troublesome and persistent weeds." ... which seems a bit harsh. They will add a lot of weeding work within a typical flower bed or any neighboring lawn space, but have some nice attributes for the right locations. We keep some as host and nectar plants for several butterflies in an alley border where most of the seeds get washed down the storm drain. As ocgf mentioned, flowers don't last long, but foliage can pass as a very heat and drought tolerant ground cover. Responds well to mowing or trimming to reduce the weedy look. The photo shows a small patch we have in heavy shade at the base of an American beautyberry bush; it flowers only a bit less here than in full sun, so spreading volunteers still pose a challenge. This post was edited by bostedo on Mon, Jun 16, 14 at 1:09

Maybe Scutellaria ovata. Right on with the scullcap guess.