Inside Pocket D there';s a door on the villain's side to go to the ski lodge area. Inside that building is an elf near the fire pit, IIRC, who is a vendor and can take them off your hands for some various stuff, like a badge or two, etc. I generally save mine up and get some of the Slow Resist recipes to craft and sell. It's not like a gold mine, but it's something to do with them. The other stuff the elf sells probably isn't of too much interest to most of the numbers-obsessed in the game. IIRC, I haven't spoken to the elf much lately, cashing out canes is a sometimes-only task for me.