When I was a grade schooler, one of the highlights of visits to my cousins in Stow, OH, was the Indian tree. It was a huge old oak, bent at the base to point south. It was wonderful for climbing, fantasies, and a great area to pick blackberries. Such trail marker trees are sometimes called thong trees with the idea that Indians bent them and held them with thongs until they grew in position. Of course, young trees can be bent by nature, perhaps a larger tree that fell. If the bent tree is much less than 30 inches through, it is too young to be an Indian tree. Sometimes they're found in far-apart rows over a large distance, clearly marking an old trail. Now there are groups like the Great Lakes Trail Marker Tree Society that mark and memorialize these trees.
This illustration is of red oak male flowers, hanging in the wind to spread their pollen.