Well, I am a librarian by degree, and formerly by practice. I have learned that once a librarian, always a librarian. It's like a sickness. I rearrange books at every library I visit. My homeschool shelves are in Dewey decimal order (mostly). And best of all, I love to incorporate all types of books into my homeschooling.
Let's start with math.
You may not think that math lends itself to picture book and juvenile non-fiction supplements, but it does. How much drill can our poor children take? I'm bored just assigning it.
These are just a few math books written by Matsumasa Anno. A number of questions are asked about each illustration. The reader is asked to add, subtract, compare, estimate, etc.
Stuart J. Murphy is, in my opinion, the king of math non-fiction for young readers. Pick a math concept, and he has likely written a book about it. This is just one example. In this book, the reader looks for matches to socks. It's useful for matching, pairs, and even numbers. As a bonus, this particular book is illustrated by Lois Ehlert.
We actually watched a Reading Rainbow video of this book, where the original illustrations were shown while someone read the text. A great book for your math student who is obsessed with giant numbers.
This is a simple, repetitive introduction to addition. My 5 year old loved it, and by the end had figured out the pattern to the text and was "reading" along.
I love Tana Hoban! When my kids were in preK and K, we read her books every chance we got. They are so simple, with everyday things that are familiar to kids. Highly recommended.