[Trillium]

Yorkie, that's why I included the link. If you look at wizzywig's picture, specifically at how the cluster of shoots comes out of the main joint, at the long spacing between the leaves and the longer smooth-edged leaves, it strongly resembles the bindweed pic. Your celadine pic leaves are rounder and have more scallops.

The link I sent is only one variety of bindweed. Sadly, there are lots more varieties