So easy and reversible! So adjustable!
This tidy edging is from 1902 Butterick Publishing’s Fancy and Practical Knitting, p. 51, #79. It can be ANY width from 10 stitches to whatever you need in increments of 4 stitches! With just 8 easy pattern rows (4 of them are just knit across), this edging is easy to memorize and will work up quickly.
The narrow sample is 1.5 inches wide with the minimum of 10 stitches at cast on.
The wider sample is 3.25 inches wide with 22 stitches at cast on (four 4-stitch repeats and 6 edge stitches).

Skills needed: cast on, slip purl-wise, knit, yarn over, k2tog and bind off in knit stitch.

Gauge is not important in this pattern. Any block-able thread/yarn will work. Make a swatch to check size and appearance.

40 yards of #10 crochet cotton thread will make about 10 inches of 22-stitch-wide edging in the stated gauge.