The facebook page for the Costumer's Guide had a post a few weeks ago--a theater in Kalamazoo didn't have the space to store all of their costumes, so they were giving away some of the more damaged pieces. They went so quickly--I saw the post four hours after it was made, and managed to get one dress. It arrived last week and it's actually in pretty good shape.
The theater said it was a 1930's day dress. I'm not sure if it's silk or rayon, I didn't do a fiber test but I feel it handles more like rayon.
Most of the damage is the fabric splitting along the neckline (and I know having it on the hanger isn't helping, I removed it after the pictures).
Selfishly I wish I had seen the post earlier, they had some amazing things that would have been great just to have for pattern purposes. But at least I got something--I wasn't able to sleep, so about 3AM got online and saw the post. The dress looks as though it might actually fit me, but given the condition it would have to be for something special.