I'll nominate
Anne of Green Gables a novel by Lucy Montgomery. It was actually written to be enjoyed by all ages but is usually regarded as a Young Adult classic. It's right here:
https://www.mobileread.com/forums/showthread.php?t=24988
but is available in many formats and is in Project Gutenberg.
Here's a little review from an Amazon reader:
"This is a gentle coming-of-age story set in late-Victorian Canada. Anne is an orphan adopted by a middle aged brother and sister, who originally intend to offer a home to a boy who can work on the farm. Anne is a fiercely imaginative and impulsive child and the story follows her life from age ten to sixteen, as she involves her friends in all manner of exploits. The countryside is an integral part of the narrative and is affectionately described. The story is warm-hearted, but pulls back from being sweetly sentimental."