I have two for you:
My father used to sing us to sleep with Tennyson's "Sweet and Low." The second, Kipling's "Seal Lullaby," I remember from high-school chorus.
Here is the website for those and a few others: http://www.babysstory.com/StoryPages/PoetryMain.htm
The music for the Kipling piece can be had at the following website: