Alliteration is the repetition of the initial consonant sound. There should be at least two repetitions in a row. An example is - She sells seashells by the seashore. The first letter, s, is a consonant. It is repeated many times. These books are a great way to introduce the concept of alliteration to your students.
Three grey geese in a green field grazing,
Grey were the geese and green was the grazing.
-Three Grey Geese, Mother Goose