I love looking at this website. It's an outgrowth of a bookstore in northern Ohio. The owner, whose name is Harriett Logan, lets people send in the plots of books they remember reading as children but they can no longer remember the title. Others out there make suggestions as to what the title might be.
It costs $2 to submit a book stumper but nothing to contribute ideas for titles. I look at the new listings every week.
There are other listings beyond what you see on the main page--older book stumpers that haven't been solved, plus an alphabetized list of those queries that have.
https://www.loganberrybooks.com/stump.html
I have had several of my own book stumpers solved, and have contributed a number of suggestions for others' stumpers.
Mary