When I was in grade school, anything that had "lost" or "mystery" or "secret" in the title, I devoured like candy. These include the Nancy Drew and Hardy Boys mysteries.
When I reached about 5th, 6th grades, I started reading classical literature. I even tackled War and Peace.
My mother bought a set of Readers Digest condensed books where you look at one side and there's one book, then flip it over and on the back there's another book cover. Some of the titles Were Tom Sawyer, Huck Finn, A Connecticut Yankee in King Arthur's Court, The Prince and the Pauper, Little Women, Little Men, which was a sequel or companion piece to Little Women. There were about a dozen in the series and I read every one of them.
And when a great uncle died, he didn't have any relatives except us, so we inherited his VERY large collection of hardcover books. He loved the westerns, like Zane Gray and such, but there were other books as well. There must have been 3-400 hardcover books in the collection and I read every one of those too. I didn't get out much because I always had my nose in a book. I think the Readers digest books stoked my love of classic literature, because I read just about every one I could get my hands on.
Also, when I was 12, I spent a summer down in Missouri with another uncle and aunt, who were childless. They left me at home quite a lot because she had a job and he was a farmer, but he rarely took me anywhere with him, I suspect because he was off drinking and gallivanting. She had a very large collection of Agatha Christie books in paperback, so I spent all summer reading those when I wasn't fishing in one of their 7 ponds on the farm.