The Mystery Tool, published in the May 5 Pelican Rapids Press, is a carpet-stretching tool.  The year 1876 is stamped on the handle.  Recognizing the device was Dave Osten, who phoned into the Press.  His grandfather, Norwegian Grove farmer Ole Osten, had one—and Dave still owns it today.   

Also phoning in with the correct answer was Mary Seidel, who said her husband Merle knew exactly what it was.