Stone structures in Rhode Island often are marked with bent trees. Most of these bent trees are large and over 100 years old, but many are much younger. This continuing custom of tree-bending was mentioned by Mavor & Dix. I always note and photograph bent trees, and have found that they fall into two general categories.
1. Bent trees formed with rocks.
The rocks are placed on a sapling, and it grows to form an L-shape. Here is a young tree on an outcrop with a propped boulder. The stones are still in place.
2. Bent trees formed with thongs.
This type is common in former Cherokee lands, where they are called "trail trees" or "thong trees". The sapling is bent over and tethered to the ground with a thong or wire. Here are a couple of examples.
One of my favorite bent trees is this one, at the edge of a cliff overlooking a swamp.