A lot in a bookstore. Just look books for children.

there are books for kids they are written with both characters and pinyin

You can go to Amazon to buy, many of these books

The best way to get the book you expected is to go have a look in bookstores instead of asking recommendations here, really , i mean it, you can particularly look for some children books. Or you can input some key words on the search engine of some online shopping websites, but still it's harder to know what's inside the book even if you find some.