I really hate to throw away the bits of smocking cut from the yokes of dresses to form the neckline. In the case of the recent Splendour in the Grass dresses, the cut-out piece was of reasonable size, as the neckline is fairly low.
The trickiest bit was neatening off the top edge of the smocking scrap so it wouldn't fray.
I backed this scrap to the top of the smocking with fabric.
I then cut a round shape - dictated mostly by the shape of my fabric and smocking offcuts - four times from the fabric and twice from batting. I made two sandwiches of fabric and batting and roughly quilted the sandwiches.
I added the piece of smocking to the bottom of one of the sandwiches to form a pocket, then bound the top and attached a strap.
Result: a bag to match the dress.
I repeated the process with the chambray off-cuts and a slightly different shape.
Equally good result.