"What are those seed-like things hanging from spider webs from my trees?" the lady asked.
First of all, what she saw were not seeds and they were not hanging from spider webs. What she saw was the last instar larva of resplendent shield bearer, Coptodisca splendoriferella, wrapped in leaf tissue, hanging from a silk thread it exuded.
The shield bearer larvae live as leafminers within leaves of apple, cherry and poplar trees such as cottonwood. When the larva matures, it cuts out shield-shaped portions in the upper and lower surface of the leaf mine and attaches them to itself with silk thread, forming a case.
The shield-bearing larva then attaches a silk thread to the leaf and lowers itself to the ground. When the shield-bearing larvae reach the ground they find shelter such as leaf litter or soil cracks to spend the winter. The larva pupates in the spring and emerges as a minute moth.