Toy Gnomes
Yesterday evening, a conversation between me and Mariel: 
Me: "Why is there a big pile of sand next to and under the couch?" (not asking about her shoes, sitting next to the pile).
Mariel: "I don't know.  It was someone else."
Me "Noella?"
Her "No.  Must have been someone else."
Me "Who else could it be?  Daddy?"
Her "No.  I think it must have been the toy gnomes.  Yes, mom, it was the toy gnomes."
Me (wondering where this would go. "Oh, ok.  I guess that is what happened." I swept up the sand.
A few minutes later she told me she did not think it was the toy gnomes and it might have been her, by mistake.  But she sort of forgot about it.  And she forgot that she was not supposed to dump the sand out of her shoes in the house.  I said that I was glad that she told me the truth, because otherwise the toy gnomes would have gotten in trouble for something that they did not do.  They might not even have been allowed back. She agreed that she made a good choice by telling the truth, and said that she would try to remember where to dump her sandy shoes for the next time.
I am very relieved, because if I had to ban toy gnomes from the house I would have to come up with some new creature to threaten to take away toys.  For my sake, I hope the toy gnomes continue to behave themselves.