Lullabyes are among my most favorite songs. John O'Dreams has already been mentioned; some other favorites:

Wynken, Blynken and Nod
Dance to Your Daddy
Little Man, You've Had a Busy Day
Skye Boat Song
Hobo's Lullaby
That Sly Old Gentleman from Featherbed Lane.

I'd love to hear the Gartan Mother's Lullaby--the words are wonderful.