Why does my dog destroy things the moment I leave the room?

She is only allowed in one large room due to landlord conditions and she has a large yard to play in, however, if I leave her in that room even for 1 minute alone while I go into the kitchen, she will get into something or destroy something!! When I am with her she is a complete angel and doesn't do anything bad. Why does she do this and is there any way to make her stop besides crating her? She was an abuse case and was stuck in a crate most of her puppy life. She just ate a whole bag of marshmallows that she pulled off of our mini fridge, so I scolded the bag and put her outside.