Once again distracted, I decided to try a crochet puff stitch to add some texture to a hat. And again, my circle expanded flat instead of nice curve, so I finished it as a beret rather than a beanie.

A puff stitch uses techniques from both increase and decrease stitches. Essentially you increase six double crochets in one previous stitch and finish by decreasing them all together so the stitch count doesn’t change. The width of the row does, however, which is why my circle just kept expanding.