Robert Hass was U.S. Poet Laureate from 1995 to 1997; during that time, he wrote weekly newspaper columns about poetry, which were later collected in the book Poet's Choice: Poems of Everyday Life. Most of poetry in the book is for grown-ups; you'll find works by Galway Kinnell, Jane Kenyon, Gary Snyder, Langston Hughes, and many others.
But there's also a thoughtful short essay on building poetry collections for young children. Hass first talks about Mother Goose, mentioning that "part of the pleasure of the poems is that they are also a kind of archaeology of the language." He goes on to say,
So a child's library begins with Mother Goose, and, I think, right next to it should be a songbook. For a couple of reasons. One is that it's as much a pleasure for parents and children to sing as to read together, and another is that there is more American folklore in the songs and so it adds our own historical experience to the English world of Mother Goose. And the logic of the songs belongs to the same magical world.
I haven't seen the songbook that Hass recommends—Go In and Out the Window, published by Henry Holt and put together by the Metropolitan Museum of Art—but, with some sixty songs, it ought to be well-worth seeking out. I have read Poet's Choice and highly recommend it.
You'll find links to other poetry-related posts at the blog HipWriterMama, who is rounding up the rhyme talk among the children's book bloggers today.