Alliteration

Repeating a single letter of the alphabet or a combination of letters: Sally Snake slowly slithered across the soggy swamp.

Look at the following books for other examples:

Book Title Author AR Level
Bootsie Barker Bites Bottner 2.6
Dr. Seuss' ABC Seuss 2.1
Fox in Socks Seuss 2.1
June 29, 1999 Wiesner 3.6
Lilly's Purple Plastic Purse Henkes 3.1
Sheep in a Shop Shaw 1.1
Some Smug Slug Edwards 3.3