What is The Willowware Platter?

The Willowware Platter is a rare antique dish Anne borrows from Diana's Aunt Josephine on behalf of Mrs. Lynde and a church event. Davy accidentally breaks the platter when Anne leaves it on the stairs. Anne and Diana have an amusing adventure trying to find a replacement dish when Anne falls through a shed roof trying to peek into an absent neighbor's pantry to see if she owns the same platter.