Still visible on some bare trees out there, these hanging gardens are the cocoons of a bagworm moth in the family Psychidae.
There’s a caterpillar in here who made this hanging tent of leaves last year so it could overwinter. There are some 1300-plus known members of the Psychidae world-wide. The better known in our region use conifers, but some will use deciduous trees, gathering material from the tree to make the shaggy cocoon.
I had at first thought these some new to me form of gall, but bugguide.net set me right.