This poem may be free verse, but it's got all kinds of delights going on in the sonic department. Let's break it down:
Line 1: Alliteration alert! "Houses" and "haunted" both start with the same consonant sound. Line 2: Internal rhyme, anyone? "White" and "night" were made for each other. Line 3: Consonance. "None are green." Gee, thanks for all the N sounds, Wally. Line 4: Near rhyme—it's close enough. "Green" kind of sounds like "rings." Okay, it's not perfect. But that's because it's a near rhyme, or slant rhyme. Line 7: Near rhyme strikes again. "Strange" and "rings" sound a bit alike. Line 15: Assonance—your new best friend. "Red" and "weather" have rhyming vowel sounds.
That's an awful lot of repeated sounds for such a tiny poem. What's the effect of all that? Well, for one thing, it helps tie the poem together—to push you through those short lines as a reader. In short, they help the poem feel like one thought, rather than a progression or a story. We come away from the poem with one impression left in our minds: imagination is better than… well, just about anything.