Seed stitch is a good choice when you want a cowl that looks finished on both sides and does not curl at the edges. Knit it flat, then seam the short ends together; the only repeating pattern is a change in the knit-and-purl order from row to row.
Choose yarn and needles
Gather about 200 yards of worsted-weight yarn and US size 8 knitting needles, plus a yarn needle for finishing. With this yarn weight, the cowl is designed to be about 8 inches tall and 24 inches around, but your gauge will affect the final dimensions.
Work a seed-stitch swatch and aim for about 18 stitches and 24 rows over 4 inches after blocking. If you have more stitches per 4 inches, try larger needles; if you have fewer, try smaller ones.
Knit the seed-stitch fabric
Cast on 36 stitches. For Row 1, repeat knit 1, purl 1 across. For Row 2, repeat purl 1, knit 1 across; continue alternating these two rows so each knit stitch sits above a purl stitch.
Continue in pattern until the piece measures about 24 inches from the cast-on edge, or adjust the length for a closer or looser loop. Keep the edges relaxed rather than pulling the first stitch tight, which makes the eventual seam easier to work.
Finish the cowl neatly
Bind off in pattern, then lay the fabric flat and bring the short edges together. Use the yarn needle to sew a flexible seam, matching the seed-stitch texture as closely as you can. Weave in the ends and block gently according to the yarn label before wearing.