Years ago I was asked to play this for a memorial service, and was embarrassed that I did not know it well enough to "fake"...
Earlier today, I cam across this in a book entitled "Specimens of Various Styles of Music", compiled by William Crotch (1775-1847), an important English composer and organist in his day.
The text of "Flowers of the Forest" is a lament for the army of James IV, the flower of Scottish manhood, slain with their king on the field of Flodden, September 1513. Although the original words are unknown, the melody was recorded c. 1615-25 in the John Skene of Halyards Manuscript as "Flowres of the Forrest", although it might have been composed earlier.
The tune shown in the manuscript here is a simple modal melody. Typical of old Scottish tunes it is entirely pentatonic, with the dramatic exception of the 3rd and 5th notes of the second line which are the flattened 7th.
Powerful solo bagpipe versions of the song are used at services of remembrance, funerals, and other occasions; many in the Commonwealth know the tune simply as "The Lament" which is played at Remembrance Day or Remembrance Sunday ceremonies to commemorate war dead.
Being glad that I had at LAST found this, I decided to "improvise" a performance of it, so, this is what you'll hear. I've done two "verses" in a simple manner, and hope that the added "drum beat" in the pedal isn't too heavy.
The entire book may be found here: http://imslp.org/wiki/Category:Crotch,_William
"Flowers of the Forest" is # 147.