From notes to "The LOng Harvest" (MacColl and Seeger) :
Child gives two versions of 'The Three Ravens', and four of its Scots
counterpart, the 'Twa Corbies'. Bronson prints twenty-one versions of the
ballad, of which number sixteen were recorded from oral sources in North
America during the present century.
The earliest printed text (and melody) of THE THREE RAVENS
comes from Ravenscroft's MELISMATA (1611), but Ritson believed it to
be much older than that. Professor Bronson has argued convincingly that
the Corpus Christ! Carol, of which the earliest extant text was recorded
in the first part of the 16th-century, is a pious adaptation of an earlier
variant of the THREE RAVENS - a supposition which, if correct, would
move the ballad back into the 15th-century.