Ever pull out your brown sugar and find it to be hard as a rock? I usually end up tossing it and assuming it's no longer good. But, there is indeed a way to keep it soft!
Just throw a piece of bread into your bag of brown sugar. It softens it right up! And for some way-over-my-head, scientific reason, the slice of bread will not mold. So technically you could keep it there indefinitely, although that just seems a little gross. I'd recommend switching it out every so often.
So don't throw that brown sugar away - it can be saved!