I've had this wonderfully soft thick-and-thin yarn in my stash for ages now, and I hadn't thought of anything cool to do with it, but since it's really, really cold right now, I thought it was time I made myself a cowl.
I didn't use a pattern for this. I just used a large hook and the woven crochet stitch, and made a large rectangle. I didn't make an actual buttonhole either, the gaps in this are large enough for the button to comfortably slip through.
I really like how warm and soft this is, and how it can look different depending on where I button it. For example, sometimes I like folding down the top edge of the cowl so it's a bit collar-like: