The Missing Piece by Shel Silverstein
Published by HarperCollins
The poor little circle is missing a piece. What is to be done? Off on a journey the circle goes, in search of the piece it’s missing. With many mishaps along the way, pieces are found that don’t quite fit – but come close! – and plenty of special consideration is given to what it means to be missing a piece, the story of this circle will touch everyone who reads the tale. Similar to many famous fables, the story deals with the nature of a quest, the fulfillment of the quest, and the unexpected lessons that are learned along the way.

The Giving Tree by Shel Silverstein