we were taught about this at primary school in Belfast - just before they took us to the Ulster Folk Museum at Cultra. info on the scutching process and photo of scutching mill
there is a cottage there with a scutching green..... a large grassy area out the front, and a little round watchtower so people didn't pinch your flax
from memory when the flax was pulled it was spread out then left to dry out / break down on the scutching green before it was gathered up to do whatever the next part of the process was.
I have vague recollections of it being dipped in water before being spread out to dry to help it rot a bit ..... but it was a long time ago....
hence the girl in the song would have gone out to collect the scutchslainte
alison