Our lovely NDNs have a cat that often comes over to our house and makes himself at home if they're out. He's a keen hunter cat who brings them lots of presents of dead mice, birds and the occasional rat. They're vegans and we've joked about him bringing home mushrooms instead.
Would it be too weird to put a muddy pawprint from the cat in a Christmas card and leave it on their doorstep on Christmas day with some fancy gift-wrapped mushrooms? I think it would be funny.