Immediately after posting the item above, I started another search for information and came across this recent blog post. It seems we are not the only ones curious about the origins of "May Morning Dew".

https://www.colcannon.com/blog/blog/about-the-song-the-may-morning-dew


I also did a quick look in the Sam Henry tome "Songs of the People" and May Morning Dew was not even mentioned. I find that very peculiar especially since it is old enough to be mentioned by Paddy Tunney. Although I sing the more common version of song that is listed several times in this thread, I do have a different version that has a much more archaic language I suspect is older but again I have no proof. The search continues....