My favorite book from childhood (and one I still love) is called Mandy and it’s credited to Julie Edwards, who is actually Julie Andrews from the Sound of Music. She’s written a number of books for young people. You can check out Mandy here
This particular book was about a young girl of about age 10, living in an orphanage. She discovers an abandoned, but very sweet cottage, on the other side of the wall from the orphanage. Of course she’s not supposed to be over there, but she ends up tending to the little cottage, cleaning it and planting flowers and shrubs, making it her own. One day, she goes to the cottage and it starts to rain and she becomes ill and disoriented. The orphanage Matron reports her missing, and only the “tattling” of her roomate gives a suggestion as to where she might be found. Of course the cottage is owned by a young married couple with a son about Mandy’s age. The Father goes out looking for her and you can probably figure out how it ends up, but I read and re-read that book many times when I was a kid.
Another great book that I read in Elementary School was called The Saturdays by Elizabeth Enright. It’s about a group of independent siblings who decide to pool their allowances so that each one of them, on subsequent Saturdays can enjoy a really grand adventure, rather than just sitting at home trying to figure out how to acquire a bigger allowance. This book was great fun to read. You can see a better synopsis here(novel)