There's a description of the album jbeanmusic was apparently referring to at Rounder Records. There is more information in a review by The Oregon Bluegrass Association.
The CD is "The Doc Watson Family: Tradition," released in 2005 from recordings made in 1964. The singer is Doc's cousin Tina Greer.

I transcribed this from a sound sample:

... in May,
I spied a fair couple come walkin' this way,
And one was a lady, a lady so fair,
The other a soldier, a brave volunteer.

Together, together this couple did go
To the banks of ... (?) where the deep waters flow.
They set down together at the cool of the spring,
To ...