OK, it's the morning...did you call her and find out where she put your crumb blocks?
I would put a lock on my sewing room door AND a "NO Trespassing" sign as well. Your DH needs to be with you on giving boundries to HIS mother.
I am so blessed that my dear MIL also quilts and knows it would be difficult to do so without hands, so she would never dream of invading my sewing room and throwing things away. Of course, I have come home to find the kitchen table AWOL because it fit the kitchen in their new home :roll: