[Quoting F. J. Child, 'The English and Scottish Popular Ballads' V, p. 107:]

The ballad of 'Kellyburnbraes,' Johnson's Museum, No 379, p. 392, was composed by Burns, as he has himself informed us, "from the old traditional version." "The original ballad, still preserved by tradition," says David Laing, "was much improved in passing through Burns's hands:" Museum, IV, *389, 1853. Cromek, Remains of Nithsdale and Galloway Song, p. 83, 1810, gives us what he calls the "Original of Burns's Carle of Kelly-Burn Braes," remarking, with some effrontery, that there is reason to belive that Burns had not seen the whole of the verses which constitute this copy. Allan Cunningham, Songs of Scotland, II, 199, undertook "to make a more complete version than has hitherto appeared" out of Burns, Cromek, and some "fugitative copies." So we get the original from none of them, but are, rather, further from it at each step.

--------------------- Child's earliest text is that from Dixon's 'Ancient Poems, Ballads and Songs', 1846. Click on 'Farmer's Curst Wife' in the titles list of Scarce Songs 1 on my website for a version that's over two centuries earlier.