I love the history of old folk songs and their evolution through time.
You might be interested in:
http://www.csufresno.edu/folklore/BalladIndexDocs.html A database listing folksongs. "The database offers a variety of information about each song, including a brief description, a bibliography, and historical background. Alternate titles are given."
Mudcat is also good; they have lyrics, sheet music, & a forum:
https://mudcat.org/Thanks! I enjoy tracking them myself, then doing research if necessary. Sometimes you will hear a repeated lyric in blues or folk songs and recognize that it was lifted from an older tune. It's cool to go back and discover the original.
For example, compare these lyrics from the English ballad "A Brisk Young Sailor Courted Me":
"A bold young farmer courted me
He stole my heart and my liberty
He stole my heart without free goodwill
And I must confess that I love him still
I wish, I wish but it's all in vain
I wish I was a maid again
But a maid again I never can be
Since such a young fellow lies still by me
There sits a bird in yonder tree
Some say he's blind and cannot see
And I wish it was the same with me
Before I took up with your company
I wish my babe so tiny was born
And smiling on his father's knee
And I poor girl was dead and gone
With the green grass growing all over me
Go dig my grave, dig long and deep
Place a marble stone at my head and feet
And on my heart put a snow white dove
To let the world know that I died for love."
To the Irish ballad "The Butcher Boy:"
"In London city where I did dwell
A butcher boy, I loved right well
He courted me, my life away
But now with me, he will not stay
I wish, I wish, I wish in vain
I wish I was a maid again
A maid again I ne'er will be
'Till cherries grow on an apple tree
I wish my baby it was born
And smiling on its daddy's knee
And me poor girl to be dead and gone
With the long green grass growing over me
She went upstairs to go to bed
And calling to her mother said
"Give me a chair 'till I sit down
And a pen and ink 'till I write down"
At every word she dropped a tear
And at every line cried "willie dear -
Oh, what a foolish girl was I
To be led astray by a butcher boy"
He went upstairs and the door he broke
He found her hanging from a rope
He took his knife and he cut her down
And in her pocket, these words he found
Oh, make my grave large, wide and deep
Put a marble stone at my head and feet
And in the middle, a turtle dove
That the world may know, that i died for love."
To the Appalachian ballad "I Wish My Baby Was Born":
"I wish, I wish
My baby was born
And sittin' on
It's papa's knee
And me, poor girl
We're dead and gone
And the green grass
Growin' o'er my feet
I ain't no saint
Nor never will be
Till the sweet apple grows
On the sour apple tree
But still I hope the day will come
When you and I shall walk as one."
(And some of these songs contain lines that are also repeated in other ballads like "Barbara Allen.")