The Castle Corona by Sharon Creech

A significant object has been lost in the kingdom ruled by the royal family in the Castle Corona. A pair of peasants, Pia and her brother Enzio have found it, and they don’t know what to do with it. They are aware that the authorities are searching for the object, which is a leather pouch emblazoned with the king’s seal. But something holds them back, keeps them from immediately returning it. Perhaps they are afraid of being accused of stealing it. Or perhaps they are simply fascinated by the pouch and its contents, which include couple pieces of red coral, a lock of black hair tied with a purple ribbon, and a small piece of parchment on which are written undecipherable words.
Meanwhile, the king, the queen and their spoiled children, Prince Gianni, Prince Vito and Princess Fabrizia, ponder the problem of how to find the thief who has stolen the pouch. “A thief wants what he does not have,” a hermit tells the king.
Pia and Enzio have been told by the King’s Men that if they find any significant object, they are to take it to an old woman, Signora Ferrelli. But before they take the pouch, they decide to check the old woman . They visit her, and she gives them a present: a small packet that they might need.
Then more and more objects go missing in the kingdom. This gentle, mysterious and sometimes amusing story is largely about life and the search for meaning. People who live in castles don’t have the happy, perfect lives that we might imagine. And peasants aren’t always what they seem, either.