Leechbrush (Conjurer's-Nut, Indian-Olive) - Nestronia umbellula (Santalaceae)
First image shows typical four-part flower, opposite leaves. Other images show habitus, including nearby trees (largely oaks/hickories), and a five-part flower. This plant was part of an apparent clone running for about 20-30 meters along the roadside. There were many flowers, all pistillate.