Not much in Sandburg's American Songbag (1927), either:

O 'twas on a bright mornin' in summer
When I first heard her voice singin' low
As he said to a colleen beside him,
'Who's the pretty girl milkin' the cow?'"

Sandburg's notes:
The fragment here is probably a make-over, a distillation, from an Irish song of lesser grace and melody. Bob Lee sang this for me, but wasn't sure he had the words right; he would see the traffic policeman, Tom Burke, and be sure; and Burke said, "Why should ye be wantin' that little song? It's old. Everybody knows it."