I'm posting this LONG (nearly 22 years) after the original post. But I'll try not to flog a dead horse.

In P.G Woodhouse's "The Code of the Woosters", a character goes into conniption fits whenever he hears WMT because it doesn't rhyme. (A totally hilarious book, BTW.)

The quote from "Fern Hill" DOES rhyme. It's a type of rhyme called assonance, in which the rhyme is in the vowels, not the whole word:
Easy / mEans / dyIng / sEa