Part 2 because I forgot some. And honestly, after every one of these I publish, I remember some I should have put on the list and didn't. So I'll just round up a few books I forgot on the last list, and then move on out of elementary.
May I Please Have a Cookie? by Jennifer E. Morris--This is a Level 1 reader, so for beginning readers. These types of books necessarily have very simple text, and they rely heavily on the illustrations. The illustrations serve a dual purpose: context clues for early readers, and entertainment. This was one that came home from school with my first grader, and I thought it was really well done.
Hank the Cowdog series by John R. Erickson--I had never heard of these before moving to ranching country, but we have multiple copies of these in our school library. I don't know how widely available they are elsewhere, but they are worth seeking out for kids if you can find them. They are written by a guy who was a working cowboy for most of his adult life, and they're told from the point of view of a cowdog named Hank, who is Head of Security on a ranch (at least, he thinks he is). They're modeled on those old-fashioned private eye novels like Sam Spade, but they're very funny and totally appropriate for all kids. There are like 60+ of them in the series, and I would say they're for something like second or third graders.
Black Ships Before Troy and The Wanderings of Odysseus by Rosemary Sutcliff--The first of these is an abridged version of The Iliad, written in prose instead of verse. The second is the same, but obviously for The Odyssey. Both are beautifully illustrated and bound, and are a good introduction to some great stories for kids that are much more accessible in this format. They're for older elementary, probably fifth grade and up, but they would also be good for middle school or even high school, for kids who aren't ready to read the more-difficult translations of these stories.