Amy Lowell’s poem “Lilacs” features numerous instances of alliteration, which means the repetition of consonant sounds at the beginning of words.
This usage can be seen in the first stanza within four lines that include alliteration within a single line and then sometimes repeat the same sounds in subsequent lines.
Orange orioles hop like music-box birds and sing
Their little weak soft songs;
In the crooks of your branches
The bright eyes of song sparrows sitting on spotted eggs
The first line begins with assonance, the repletion of a vowel sound, in this case o. The b sound in the “box” portion of “music-box” is repeated in “birds.” In this line, the following one, and the fourth line, s is used extensively: “sing ... soft songs”; “song sparrows sitting on spotted.” The b sound also recurs, but modified as br: “branches / The bright.”
Five lines farther down, there are more s sounds; some are modified slightly as st or sh.
Settling sideways into the grass of an old road;
Lilacs, wind-beaten, staggering under a lopsided shock of bloom
In this group, Lowell uses alliteration in combination with consonance, the repetition of consonant sounds in other than the initial position: the final s sounds that appear at the end of “sideways,” “grass,” and “Lilacs,” and within “lopsided.” These lines also use l in alliteration in “Lilacs” and “lopsided” combined with consonance in “Settling,” “old,” “Lilacs,” and “bloom.”
Another group of four lines also uses alliteration extensively. Again, Lowell sometimes combines it with consonance.
You tapped the window when the preacher preached his sermon,
And ran along the road beside the boy going to school.
You stood by the pasture-bars to give the cows good milking,
You persuaded the housewife that her dishpan was of silver.
The w sound appears in “window when,” and the p in “preacher preached” returns two and three lines below in “pasture” and “persuaded,” with consonance in “dishpan.” Alliteration occurs with the r of “ran” and “road” and the b of “beside,” “boy,” and “bars.” Although Lowell’s lines are not rhymed, the repeated use of "You" to begin three lines and s in the last word of the same lines provides consistency among them: “sermon,” “school,” and “silver.”