The Braes o Balquhidder/Balquither (on which Will ye go, lassie go was based) was composed by the Paisley poet Robert Tannahill.
Robert Burns composed songs and poems. He also collected folk songs, some of which were mere fragments, and these he would repair with a light touch, just enough to make it a song again.
Burns composed and collected over 300 songs, and Serge Hovey researched the original tunes to which they were set. (Alas he died before the full collection was available as recordings - 7 cds available from Greentrax- tho the manuscripts were all completed.)
Linn released a set of 12 cds of every Burns song, put together by Fred Freeman, abd featuring a large cross section of Scottish folk singers. (Some of the tunes are not as Burns originally set them)
I like to avoid the 'usual' 20 or so songs, there are plenty of beautiful or humourous or angry or political or Jacobite or sensitive or sad or loving ones to find!