The Idea of a destroyed hat was used in several collections for example in “Prince Charming” AW10/11 and just 3 days ago in the latest Red Label show.
You can buy the same hat as used in the show at Worlds End.
But you can also make one yourself. Just find a classic men’s hat and tear it on all the major edges. Then find a nice piece of fabric and drape it around as a hatband.
Just use the fabric raw edge then everything works well together.
You might need to secure the hatband with a few hand stitches for it to stay in place. If you like a rough look, you could even apply some paint in a contrast colour to give it a special finish.