The Red Pony by John Steinbeck.
The 1945 edition of The Red Pony was the first to have illustrations, and equine artist Wesley Dennis was selected to do the job.
There are some smaller illustrations interspersed throughout the book, but this edition also has special pages that are full sized and have no text on the back.
People used to cut these out of books with a knife and frame them. Honestly, I am tempted - if I had a second copy of this edition, I just might do it!
The red pony is named Gabilan. One of my carpet herd horses is named that, but I had not remembered where I'd gotten the name. I'd searched once and found a mountain range called the Gabilan Range (presumably where Steinbeck got the name for the pony) but I did not find a connection to this book years ago when I searched. Now I know.
I am not a fan of John Steinbeck as I find his books to be depressing. And after reading The Red Pony in grade school, I set the book aside, never to read it again. But I am going to reread it and see if time has changed my opinion of the book.
And even if I end up not liking it, I still have a lovely vintage book with beautiful illustrations to put on my shelf and enjoy.