I found this by ear, since there were no chords online, so this might not be
perfect, but I find that it works pretty well. Same progression through the whole ballad.
"O where ha you been, Lord Randal, my son?
And where ha you been, my handsome young man?"
"I ha been at the greenwood; mother, mak my bed soon,
For I'm wearied wi hunting, and fain wad lie down."
"An wha met ye there, Lord Randal, my son?