Please help identify unknown root-like growth
We dug these strange things up from our back yard. We've been in this house for 25 years and have never planted anything in the area these were found. They are similar in size and shape to fingerling potatoes but many have quite a few smaller root like growths protruding from them. I've been in touch with the county extension service and they think it's a type of non showy orchard whose name escapes me at the moment. Where did they come from and what are they? Any ideas?