I think the implication is that the large box is his order, but 6 Feet^3 is just over (1.8 Feet)^2, so even with wrapping, napkins, (forks?), and anything else, the box should be less that 2′×2′×2′ (because that’s 8 cubic feet)
A mushroom is neither part of the Plant Kingdom nor part of the Animal Kingdom; “mushrooms” are various types of lifeforms within the Fungus Kingdom (but not all types of Fungi are “mushrooms”)!
If you criticize 100% of someone’s decisions, you’ll hit 100% of the “I told you so” opportunities… and they’ll want to kill you