Yep, that's what they are. I knew the hard-as-a-rock galls that attach firmly and often girdle small branches/twigs were galls but never knew what these more colorful, soft, marble-like growths were. I pick them up constantly during the summer months and just trash them. I am eliminating some wasps from growing into adults, but probably am not making a dent in this specific wasp population.
Thanks, Celia.