This plant has runners, grows along the ground. I have not seen any fruit as of yet, but I keep pulling up the plants because for a while I thought they might be poison ivy or something I am not familiar with. They tend to be in part shade to shade. Soil is clay loam. They appeared in an untilled area of the garden that was neglected, but now I see there are quite a few spread over a fairly large area. No water in that area although the clay tends to hold it.
Is this a dewberry?
no, this is not a dewberry. It is a Clematis, but I’m not sure which species. The leaves look most like Clematis virginiana, a wild native, but according to Jan Haldeman, Clematis leaves can be extremely variable, so it could also be a cultivar or a weedy species like Clematis terniflora [=C. dioscoreifolia]. They like to climb on a trellis or fence; if you support it and get flowers, please submit an image of the flowers and I should be able to give you a species name. These are popular garden plants.
Dr. Steven R. Hill, Botanist, SCNPS