I've provided a few different lists of books to get you started in your search for recommended books for K-2 kids. The first link below is a list compiled by the Association for Library Services for Children (The ALSC). The Scholastic site is organized by topic, author, genre... I've included the National Science Teachers Association's (NSTA) list of the best STEM books K-12, and The Children's Book Council's recommendations for the 2017 Best STEM books, too.
To go directly to these links, click on the blue words below. Please email me if you have more specific questions or recommendations I should add. Happy reading!!
NSTA Best STEM Books K-12
Children's Book Council 2017 Best STEM Books