I think you're pretty safe in thinking it's in the public domain, Redworm. Sandy Paton, who died this year at the age of 80, traced it back to his mother's singing. He said she sang it in Pennsylvania in about 1920, and 1923 is the cutoff date for copyright. Sandy did not specify the "toothpick" verse. He posted only one verse that hadn't been posted above his post.

-Joe-