I see "Eddystone Light" has been mentioned already, but not the Shel Silverstein poem/lyric "The Mermaid".

Both of these are in the DigiTrad, although the Silverstein given appears to be transcribed from a live version that I don't think I know -- the two recordings I'm familiar with are by way of Glenn Yarbrough and Great Big Sea, and those two and the DigiTrad version differ in the ways that live and studio performances generally do.