Owl Diaries #3: A Woodland Wedding by Rebecca Elliott
From Scholastic Press:
Eva's teacher, Miss Featherbottom, is getting married. All of her students have been invited to the wedding. And Eva starts a Secret Wedding Planners Club! But before Miss Featherbottom walks down the aisle, her necklace goes missing. Eva wants to help! She quickly turns her Wedding Planners Club into a Detectives Club. Can Eva track down the missing necklace before Miss Featherbottom's wedding is ruined?