Hello, Melinda. There is a good chance that the person you heard at camp was wrong. That is probably not a fragment of a long song. It is a modern reworking of some themes from the old ballad "The Braes of Yarrow" (also known as "The Dowie Dens of Yarrow.")

This is a common trend, supposedly - for old narrative (story-telling) works to become a source for lyrical (personal and emotional) works. Right now the only example I can think of is the "The Wizard of Oz" generating "Wicked."

The person who your song probably lived among people who were familiar with the old ballad. You can read about that ballad on Wikipedia.

I hope somebody sees this thread and provides information so you can put the song on your show. If not, get with a musician and write the melody down before it's lost forever.

Congratulations on treasuring the song so long.