Mosswine Hide is a collectable item in Monster Hunter World used to complete the delivery quest “Mushrooms: Nature’s Smelly Bounty”.
Mosswine Hide is collected from killing and looting Mosswines. They are rare pigs roaming the wilds. They appear on a few maps but the earliest opportunity is in the Ancient Forest.
You can farm it at the following location by fast traveling back and forth between maps:
This is what the Mosswine looks like (kill it and loot its body for the hide):
If you’re looking to complete the “Nature’s Smelly Belly” delivery, head back to Astera and deliver it to the Research Center. It will reward you with the “King Truffle” for the Canteen, a new ingredient to make better meals. The King Truffle is unlocked permanently and can be cooked as often as you like.