The Dark is Rising.

From The Dark is Rising Sequence. The first one moves at a clip, and the only thing that bothered me was (in my accent) the slant rhyme thaw/before. I believe it's probably a full rhyme in other accents, and presumably Cooper's. I keep finding second, and third meanings; five will return might refer to Bran, Will, and the other three kids staying and Merriman going. Or not.

I always liked the last part the best: "All shall find the light at last, silver on the tree". Perhaps it's just my liking of the word silver. It just sounds so gorgeous (and in a book that is very much Light vs Dark) and imbued with a certainty - "All shall find the light at last".

( When the Dark comes rising, six shall turn it back; )

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It took me awhile to appreciate this poem. It's much less sing-songy than the other one, which is quick to memorize and easy to set to a rhythm; this poem immediately slows down. The very first line is my favorite. It always impressed me how Cooper manages to fit the prophecy and the story together, without mangling either.
( On the day of the dead, when the year too dies )