I am sure this has been done before, but I had yarn and an idea, and figured this out by trial and error. It’s really simple, yet pretty!

With collar A Chain 18. Turn
Row 1 - sc, skipping first two chain st.,then chain 2
Row 2 - dc, beginning with the second stitch, then chain 2
Row 3 - dc, beginning with the second stitch, then chain 2
Row 4 - sc, beginning with the second stitch. Add color B. Chain 2.
Row 5 - dc in 2nd stitch, dc reaching down to row 3 post, 2dc repeat to last 2 st, one more dc to row 3 post, dc. Chain 2.
Repeat rows 4 and 5 changing between color A and B, carrying the color not used up the side.
When desired length is reached, finish with 2 rows dc, 1 row sc. Weave in the end, wash, block and wear.