I'm reading 'The Secret Rose' (and other stories) by W.B.Yeats.

In one of the stories he recounts a tale about a girl who was given a fairy knife to cut peat moss and her brothers eventually steal the knife from her and cut the hand off the fairy.

Yeats suggests that this is a Scottish song, and I found a reference in an Anne Grant essay from 1903 where a fragment of the song is translated from Gaelic.

The story also ends up in a Grimm Brothers volume.

The line from the chorus is:
"I behold yonder the tomhan covered with rowan and holly"

Have any Scots/Gaelic speakers heard of this story or song? It would be great to track down the full song in Gaelic.

I wrote my own ballad on the topic, there are links to the references I found in the video description.