Sounds like you might be on to something. I too had a couple
"volunteers" and the one I dug this morning had a few taters on it.
Not bad for letting it fend for itself all season. I think the
groundhog got most of my main crop, but he hasn't found the volunteers
yet..!

I think I'll try overwintering a couple raised beds and see what
transpires.

Zone 5, Midwest US.