Here’s another quick-to-knit reversible edging from 1889 Weldon’s Practical Needlework, Volume 2 that had no original image! The edging has 10 pattern rows with 3 set-up rows. Every backside row is: knit across, purl 1. The rows vary from 10 to 13 stitches. I fixed a small error and put in a selvage edge.
Skills needed: long-tail cast on, knit, purl, slip, k2tog, k3tog, yarn over, yarn over twice, SK2P (slip 1, k2tog, PSSO) and bind off in knit stitch.

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

2 yards of #10 crochet cotton thread will make about 12 rows (1 inch) in the stated gauge.