"There is no such thing as Arlo Guthrie's Lass of Glenshee. TLOG is a traditional song which is found extensively in Ireland, Scotland and North America."
You might think there was no such thing as Arlo Guthrie's "Gal I left behind me," but his version is copyrighted. The lyrics differ from the version collected by J. Fingers in 1897 in the following ways: "gal" is changed the the politically correct "girl". "if the Indians they don't find me" is changed to the grammatically correct "if the Indians don't find me, boys."
But Pete Seeger makes no claim of ownership for his banjo version on God Bless the Grass, which you can hear on YouTube.