Apperently the illusion of a box is as good as the real thing for some cats.
more at: https://www.dailymail.co.uk/sciencetech/article-9547407/Cats-really-love-sitting-boxes-optical-illusion.html
James cheered up once they got outside. We didn’t many mushrooms. I guess it hasn’t been warm enough since the rain.
I think it’s for the same reason cats make an effort to sit on any piece of paper on the ground: if it’s there, it must be important to you, and that means the cat is in the way, and that means the cat is better than you.