I am suddenly obsessed with the camel stitch (a hdc that is performed in the 3rd loop). This beanie is made with all hdc camel stitches.
You begin working the band on one side of the round, then you’ll turn (as you would at the end of a row worked flat), turn the beanie inside out, and work on the other side for the whole rest of the hat. This will give you a ridge-y ribbing look to the band and a bumpy oatmeal texture to the body of the hat.
Super super simple once you understand the camel stitch of working in that 3rd loop.

Links to videos showing the hdc camel stitch and decreases.