JOEY'S FIRST DAY is a practice reader at the Kindergarten level. It features one short sentence on every page, like the following:
Joey meets his teacher.
Joey is shy.
This is an older book so if you're looking for visual diversity --ie, some who isn't white-- you won't find it. The only other thing I would note is that I probably wouldn't have used this book with my children because it talks about Joey's fear and nervousness. My kids were, and still are, eager to do new things so I've always considered it unwise to suggest that others might be nervous. Basically because while eager, they are also suggestible.
Okay practice reader for the earliest beginning readers.