Any yarn, any sized hook.
Crochet a “chain” long enough to go around your head. Some like it looser, others tighter. Approx 18″.
This band is crocheted flat and the ends joined to complete.
Row 1: the chain, approx 18 inches.
Row 2: slip stitch or single crochet into each chain. Turn.
Row 3: chain 3, double crochet into each chain across width. Turn.
Repeat row 3 until you feel that it is wide enough for your taste.
Last row, slip stitch or single crochet into each stitch. Fasten off at the end. I crocheted 10 ridges.
Join the narrow ends together, and then gathered them so it looks like the picture.
The yarn in the picture is using a Briggs and Little, 2 ply, 100% woo, that was hand dyed with food grade dyes to give it a mottled denim look. 5mm crochet hook. 100 gram hank/skein produced 4 headbands. The bands were washed , treated with fabric softener, and air dried on the hat block.