The Boy on the Porch by Sharon Creech
This children's novel begins with a young couple, John and Marta, living on a farm waking up to find a young boy of about six or seven sleeping in a chair on their porch. He takes a long time to wake up, and when he does, he doesn't seem either able or willing to talk. He does however produce a note from his pocket that says "Please taik kair of Jacob. He is a
They aren't sure what to do, but offer the boy food, comfort, and other things they can. John asks some questions in town, without disclosing the situation and doesn't hear about any missing children, so they continue to live quietly.
As the days go by, and they learn what interests the boy and what he has aptitude for, they try to do the right things: find him a friend his own age, provide a loving environment, clothe and feed him. But as the new school year approaches, they feel they must make more of an effort to find out who left him and why. They approach the sheriff, a man they find gruff, authoritative, and unsympathetic, and he berates them, but also lets them keep the child for the time being.
Then the unthinkable happens, and they find their lives changed forever.
An interesting premise, and the fallout from the crisis is a story of its own, that is only filled out lightly here. John and Marta seem a good-willed couple that don't have children of their own to nurture and love, and this incident brings them a way to fulfill those needs.