How's about a quick knit.
16" circulars, size 6-8US (I used size 8)
non-scratchy yarn (I used 50% alpaca, 50% acrylic)
CO 94 sts, or enough to get gauge. See gauge calculator at bottom for those of you who want really really easy maths.
Join in round.
Knit 5 rows in twisted rib (K into the back loop, p1).
Knit 20 rows in stockinette stitch (or rows to get desired width).
Knit 5 rows twisted rib.
Bind off using favored "stretchy" method. Sewn bind off works. Or, for really easy, bind off knitting the ks, purl the ps.
Row 1: K.
Row 2 and other even rows: P.
Rows 3, 5, and 7: Kfb across.
Row 9: Bind off.
Twist into rosette and sew together.
CO 21 sts.
Knit 2 rows.
Pass all sts, one at a time, over first sts.
Twist into rosette. Stitch in place.
I needed this in particular for the yarn I used. Since it was reclaimed from a sweater, I had no idea the yarn weight. I estimated I would need the headband to be about 16 inches to fit around my head (but it's small, so a normal person might need it to be 17 inches), then knit a small swatch in st st.
CO 18, knit in st st for ~4 inches.
Use this formula to figure out how many sts you should cast on:
___18 sts___ = ___Y sts___
X inches 17 inches
where x = the width, in inches, of your swatch, without pulling; and y = the number of sts to CO for the project.
My swatch was 3.25 inches wide, so (18 x 17)/3.25 = 94.