Pigs should consume grass as sheep do, but have a chance to produce a mushroom when they do. I know that mushrooms can’t grow in the light, so they wouldn’t produce a breakable mushroom, but one that’s already broken and can be picked up.
Currently pigs lack utility compared to the other animals. They’re less useful for slaughter because unlike cows, chickens, and rabbits they don’t drop anything in addition to meat. They also aren’t useful to keep around alive, because they don’t produce a resource like sheep do, are not useful as mounts as horses, donkeys, and llamas are, and they provide no defence as cats and dogs do.
This would gives another purpose, and one that makes sense for pigs to have (truffle pigs find mushrooms in real life), and would provide a new source of mushrooms.
Thanks for your time and consideration.