Swish Worsted in Gulfstream. One more to go.
CO about 78 sts, join in the end, K until you have 5.5-6.5 inches, depending on size, do a round of K1, K2tog, then K2tog until you have about five sts left. Work I-cord for a few inches and tie in a knot, or just run the yarn through the sts on the needle and tie off. The brim rolls up, and you and roll it up or down to make it larger or smaller. Great mindless knitting. I did one in the dark once, proving I can still knit if I lose my sight. You can make them larger or smaller by using thicker or thinner yarn, adding or subtracting sts from the CO, etc.