I have recently found a group to donate a bunch of my yarn to! I am really excited about this, and in the future, I intend to not buy as much :joy: Anyway, this group makes charity projects and are asking for nightingale type capes. I found this one- I love it- but how would I go about doing a button hole? The pattern only shows fastening with a brooch.

It looks like the ridged trim at the neck is a perfect place for a buttonhole. You could do a yarn over, k2tog for a small buttonhole or maybe work a buttonhole like this one for a larger.

Good you found a charity that can use your donations.