Besides The Scots Musical Museum, the tune is also in The Poems and Songs of Robert Burns, 3 vols., edited by James Kinsley (Oxford, 1968), and in The Songs of Robert Burns, by James C. Dick (1903; Folklore Associates, 1962), both with commentaries; the latter's title being "Sae flaxen were her ringlets". Linn Records is now publishing "Robert Burns: The Complete Songs" in 12 vols., but, in 7 of them that I've got, "She says ..." is not. Let's wait for other volumes to be released.