Probably The Wheel on the School by Meindert Dejong:
“Why do the storks no longer come to the little Dutch fishing village of Shora to nest? It was Lina, one of the six schoolchildren who first asked the question, and she set the others to wondering. And sometimes when you begin to wonder, you begin to make things happen. So the children set out to bring the storks back to Shora. The force of their vision put the whole village to work until at last the dream began to come true.”
I don’t know why it was a favorite, why I even read it, or where the hell I got the book from, but I loved it and plan to read it again when I have time (yes I still have it on the bookshelf).
If it was slight older than childhood, say early teens, than I would have said The Masters of Solitude and Wintermind which are two books I recommend to everyone!