It probably was not lost to Toby. He probably knew right where he put it sometime last summer on a day when I didn't manage to intercept his trip outside with my boot. By the time the snow came, I gave up hope and replaced them.
Somewhere in my psyche there must have been a grain of faith because I didn't discard the remaining boot, the left boot, the one on the right in the photo.
Today the right boot came back. I walked around the house, and there it was between house and dog pen, as if it had just been brought outdoors in the mouth of a boot and rock loving dog.
It is not in bad shape, all things considered. It doesn't appear to be much worse for spending the winter outside under snow--a little algae, a little damp, but it does not seem to have been buried.
There must be a moral here somewhere, but for now I am just enjoying the surprise.