Found!

On a hunch, especially after an almost-thorough cleanup of my bedroom, I had Bruce call mother to see if the missing ball was there. At first she said it wasn't there. Then, 15 minutes later, she calls and says it's there, after all. Whew . . . it will be retrieved when we stop by later this weekend, given a good scolding and spanking for measure, and then put to use to complete the vest in time for the next cold blast.