Found while seeking Tommy Boy (I just understood the clue this afternoon in the car. duh!).
These are kind of fun to find. You can find masses of spittle on leaves and stems. There are many spittle bug species. I don't know that I'll ever know what kind it is since I didn't see the animal itself.
The adults are sometimes called froghoppers -- they hop from place to place instead of flying. They look like a little shield, matte finish.