This is a light silk hat suitable for chilly autumn days. The silk makes it very soft and lightweight.
The hat is knit as a rectangle which is the seamed at the back then stiches are picked up around the edge and knit in the round to make the top of the hat. It is based on the seafoam stitch. A good tutorial can be found on:
http://www.knittingdaily.com/media/g/knitting_daily_tv_vi... Wrapped Drop Stitch with Eunny Jang, from Knitting Daily TV Episode 904