Tar Heel Reader has a collection of free, easy-to-read, and accessible books on a wide range of topics designed for beginner teenage readers.Its an American site and each book can be speech enabled (with the American accent) It can be accessed using switches, alternative keyboards and touch screens The books may be downloaded.
I have just used I Love You as part of my Valentine's Day Project.We put it on the whiteboard . The readers in the class read page by page by and early readers were able to join with the repeated "I love you" written in every picture .
You might also find Looking for Signs (from a UK author) useful for Health and Safety
Read a review of Tar Heel Reader on Paul Hamilton's blog