Even though this is a sonnet, it doesn't have a formal rhyme scheme. To make up for this lack of formality, Rita Dove weaves in some sneaky sound effects to make her poem sing. Let's get a quick line by line of what's going on with sound:
Line 1 flows along pleasantly with lots of O and N sounds. The higher-pitched verb sounds (the ee in 'ordinary' and in 'beautiful') help the line feel like a rising melody.
Line 2 echoes back some of the same words and ideas as the first line, so it makes sense that we still have short O's and N's. The L sound echoes on this line and gives a partial rhyme to line one. See? It's all coming together.
Lines 3 and 4 repeat several P sounds, which pump up the pain of Persephone pulling. (See what we did there?) It's a sound that builds momentum behind the lips and then pops with a sudden effort. Isn't that the same sort of sound you'd expect to hear pulling a bulb out of the ground?
Lines 5 and 6 both have consonance, or repeated consonant sounds, but with different effects. The phrase "glittering terrible" repeats those liquid R's and L's that combine with the T to sound all bright and sparkly. Then we get that harsh K sound from "carriage" and "claimed" that really gives Hades's entrance an edge.
The last two lines of the first stanza give us the ol' familiar O's and N's as well as the rhyming pun of "heard" and "herd."
The four lines of the parenthetical statement (9-12) use two sound techniques to make us hear a mother speaking. First, there's the alliteration http://www.shmoop.com/poetry/how-to-read-poem/poetry-glossary.html ("straight to school") and consonance ("answer to strangers") that makes these demands sound like well-worn sayings. Dove also very sneakily makes it sound like the mother begins to yell at her child by placing shorter vowel sounds at the beginning of the phrase and letting them grow longer and louder at the end ("Stick with your playmates. Keep your eyes down").
The end of the poem reminds us that this is a cautionary tale, because almost all the vowel sounds are low oo's and ow's. Also the more predictable rhyme scheme at the ends of lines in this stanza gives us a more motherly, formal sort of feel. This feels more mature, wiser. It resonates with a somber tone.
What's the point of all this? We're glad you asked. It's clear that Dove is a master of matching the sounds to the meaning of the poem. So make sure you read this one out loud, paying close attention to the music of the poem, as well as its words.