Alliteration is the repetition of consonant sounds in a series of words. If the consonants are the same but the sounds are different they do not alliterate. eg. By chance or nature's changing course untrimmed", Sonnet 18, W. Shakespeare
Peter Piper picked a pack of pickle peppers is an alliteration.
those are more like tongue twisters but you get the idea....
Great Aunt Nellie and Brent Bernard watched with wild wonder at the wide window as the beautiful birds began to bite into the bountiful birdseed. By Dorie Thurston from Thank You for the Thistle.