Hi, everyone. Please excuse me if I am repeating any information that you already know. This is the first time I have posted any message on a noticeboard...
I have been performing The Three Ravens since 1963 (I think it was 1963 - such a long time ago).
I am also an historian and have this compulsion to research any Traditional songs that I sing. So much easier now with the Internet. At The Contemplator's website is a very good provenance about the song The Three Ravens - Child Ballad #26.

This ballad dates back to 1611 where it appears in Melismata. Musicall Phansies Fitting the Court, Cittie, and Countrey Humours by T. Ravenscroft.
It is also known as The Twa Corbies.
According to the The Viking Book of Folk Ballads of the English -Speaking World the song deals with primitive superstition.
"Perhaps in the folk mind the doe is the form the soul of a human mistress, now dead, has taken.
Or it may be that the doe was considered an animal - paramour of the dead knight.
Most probably the knight's beloved was understood to be an enchanted woman who was metamorphosed at certain times into an animal."

THE THREE RAVENS
There were three ra'ens sat on a tree,
response: Down a down, hey down, hey down,
They were as black as black might be,
response: With a down.
The one of them said to his mate,
Where shall we our breakfast take?
response: With a down, derry, derry, derry down, down

Down in yonder green field,
Down, a down, hey down, hey down,
There lies a knight slain 'neath his shield,
With a down.
His hounds they lie down at his feet,
So well they do their master keep,
With a down, derry, derry, derry down, down.

His hawks they fly so eagerly,
Down a down, hey down, hey down,
No other fowl dare come him night,
With a down.
Down there comes a fallow doe
As great with young as might she go
With a down, derry, derry, derry down, down

She lifted up his bloody head,
Down a down, hey down, hey down,
And kissed his wounds that were so red,
With a down.
She got him up upon her back,
And carried him to earthen (I sing 'lac')lake,
With a down, derry, derry, derry down, down

She buried him before the prime
Down a down, hey down, hey down,
She was dead herself ere e'en-song time,
With a down.
God send every gentleman,
Such hawks, such hounds, and such a leman.
With a down, derry, derry, derry down, down
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I have a copy of the original music as in the Melismata - I can email it to anyone that wants a copy.

In the Melismata version
The 1st line is repeated again to make the 2nd
& 3rd verse lines. With the 2nd line (above) becoming the last line of the verse.
- - - -
'Leman' (Leman used in the Melismata version, 1611)
lem·an (lĕm'ən, lç'mən) n. Archaic.
A sweetheart; a lover. A mistress.
[Middle English leofman, lemman : leof, dear (from Old English lçof) + man, man; see man.]
- - -
As to the use of 'a doe', this may have an Old 'secret meaning' but think it is just a term of endearement as we still do today ('Hen', 'Duck', 'Pigeon', you 'little Monkey, etc..etc..)
- - - -
The song, although sung slowly, gives the feel of being a slow dance song.

I hope I have not spoilt the thread by giving all this information. I find it really fascinating to find other versions and try to unravel how songs change - just like Chinese whispers!