You can buy this pattern individually or as part of the Spare Boomerangs ebook (4 patterns for 7 euros).

Easy to knit, Easy to wear.

Knit and purl stitches for texture (two different sides).

Boomerang shape.

The stitch is called “seaweed” but as Heather2009 pointed out it really looks like sand ripples.

Thanks to the testers:

sdtilepcs
lalalemon
unitwo
vangie
roxyrob
paulinespinks