Feeling a little better now, Jim? Having given your request considerable thought, I put my vote in for Northern Lights of Labrador - it's a beautiful song that deserves a wider audience.

Having said that - I don't know if it's public domain; it's a fairly modern song.

"The composer of Cape St. Mary is still alive. (or at least he was a couple of years ago)" -

I believe he's been gone for good while now, Jim ... I think time's starting to slip away on you ...

I can't really choose among those others I listed; they're all great songs.