One of my favorite things to do is look through pattern books. I'm one of those that start at the back and work my way to the cover. I scan pictures, visual elements then I'll go back and read lol. Anyhow, several months ago, my sister and I were flipping through and this zipper flower on a cuff.
Start by making a straight stitch along the bottom of your zipper with the teeth up. You can use varying lengths. It does not have to be exact. Mine were probably about 1/4-1/2".
When you get to the end, start pulling on your thread to get it to curl around and ruffle. You can pull with your hands to adjust it how you want.
Finish gathering the edges of the zipper and mold it into a circle
secure the back by sewing stitches through the layers of the zippers.
Add a button or whatever you'd like and your are done.