If, as someone previously suggested, it was displayed at nursery/school with a 'Found' sign on it, wouldn't dd just ignore it (and you could say 'oh, looks a bit like our strawberry, doesn't it' if she wasn't taken in by it. If, however, she thinks it looks like her strawberry then you can say 'oh, thank goodness, we've found her'. That way you could cover her disappointment (if indeed disappointment it is) by explaining that someone else had lost their strawberry too