Not sure what this is, possibly an insect nest/cocoon? I noticed on my Redbud after the leaves dropped. Thanks.

Its a Praying Mantid egg case. Lucky you!

They will hatch in the spring.

Round (rather than elongated) shape suggests a Chinese praying mantis.

Start watching for emergence when it warms in the spring, maybe mid-May in your zone (?). Dozens of itty bitty babies will hatch, not all will survive.

To catch these guys hatch... I placed the egg case next to garden path where I walked daily, and still coulda missed it... they dispersed very quickly.

Very cool, Stone!