Any sort of sport weight metallic/cotton/synthetic yarn of yellow(ish) color - 1 ball of 50 g
Set of double pointed needles (dpns) of appropriate size (see your yarn label), mine were US#2.5 (3mm)
Stitch marker (optional)
Tapestry needle for grafting
Cast on 28 stitches using magic cast on or any other provisional cast on method, and prepare to knit in the round on two dpns. (If you'r not a big fan of grafting, cast on and bind off just as you wish and sew a back seam afterwards :))
Knit 2 rounds, mark the beginning with a removable stitch marker. This is to indicate the straight (or bottom) side of the crown.
Next row begin increasing as given below:
*(1): K13, M1, K1, turn to another side, K1, M1, K13 to the end of row (30 sts)
(2): K14, M1, K1, turn, K1, M1, K14 (32 sts)
Continue increasing like this every row until you have 48 sts (or 24 sts on each of your working needles)
Knit 1 row without increasing. Next row begin decreasing:
(1): K21, SSK, K1, turn, K1, K2tog, K21 to the end of row (46 sts)
(2): K20, SSK, K1, turn, K1, K2tog, K20 (44 sts)
Continue decreasing like this until you have 28 sts (equals to 14 sts on each of the two needles)
Knit 6 rounds without decreasing and start increasing from the symbol *.
When you get enough zig-zags (my number was 11, and the length of the finished object was 23,5 inches), knit a couple of rounds on 28 stitches and then graft the live stitches with the kitchener stitch to the cast on edge, using a tapestry needle. Be sure not to twist the headband when you start grafting.
If you omitted the the grafting step, bind off using 3-needle BO or Russian grafting technique, or whatever you like, and then sew the back seam of your headband.
As an option you can leave it opened, and add button or velcro closure (the loop for button can be made as a crochet chain). My yarn contains nylon fibers and it is stretchy enough, and I just sewed the headband. I can wear it over the hair and even over a hat :)))
SSK = Slip 2 stitches, one by one, knitwise, put them back on the left needle and K2tog tbl
M1 = Pick up the bridge of yarn between two stitches in the previous row with your right needle from the back. Put the tip of your left needle into the space, and with the same movement K1 tbl