I'm surprised no one has mentioned the gorgeous West Cornwall pub song, "Lamorna" ("Away Down to Lamorna"). I was stunned when I first heard the recording of this by an uncredited singer--it's the late great Cornish singer Brenda Wootton--on the following site.

http://www.trelawnys-army.org.uk/ta/tasongs.html

While the song is originally an English music hall number, there is a Cornish-language version. See discussion thread in the archive...I won't attempt to summon it as I'm afraid of losing this message. (Not real adept at making links I fear)

Bob