Upcycled historic costuming tutorial: Turn a straw tote into a bonnet
Start with a large straw tote. Make sure the tote will be deep enough for your finished project; in this example, the tote I am using had a colored border, so I had to factor in removing that.
Remove the handles and lining (if any). If necessary, snip and unwind some of the straw to reach the desired depth. You need to unwind and save at least three wraps worth of straw to use in a later step. Cut the bonnet shape out of the tote. I don't have a pattern to share; you could adapt a pattern from a historic pattern company, or just try it on your head and keep trimming until it looks right. Make it a little deeper than you think you will need, as you will lose a little depth when you make the crown.
Unstitch the back a little - you will be folding this over the side to make the crown of the bonnet. You can soak the bonnet in water to make it easier to shape.
Fold the side edges in towards the middle back and fold the unstitched back portion over them to make the crown of the bonnet. Sew this in place. Then stitch the unwrapped straw you saved earlier around the outside of the blanket, with one layer on the inside and one on the outside, sandwiching the rough edges between the strips.
You may line the finished bonnet if desired, and trim it with ribbon or other trimmings.
Tote bag bonnets work very well for getting 1840-60s shapes, but they are plain enough that you can use them for a variety of periods. Here's the finished bonnet in action with a ca. 1909 regency dress.