This is Katharina Nopp’s hugely popular slouch hat: Wurm. It’s a free pattern on Ravelry, available in German, Finnish, French, Italian and English. I chose English.
I know this stitch as a variant of “Quaker Rib.” It’s a wonderfully rhythmic knit. Once you make a quick review of the pattern, you won’t be needing to consult it again until the crown decreases. The band uses an easy “tuck” stitch that results in a warm, firm fabric.
Wurm is knitted here in Stonehedge Fiber Mill‘s “Crazy Mill Ends.” It’s basically a DK weight, with surprises of color and even fiber. The pattern is a real yarn-eater. Mine took about 315 yards.