Wealth. Prosperity. All things come to those who own this item.
Made from the milk of Infernal cattle, the Wedge of Cheese is occasionally inserted into mortal society by forces unknown. No baatezu can claim absolutely that they made it or inserted it into their schemes, because it shows up from time to time without their doing. Or, usually, their knowledge. The Wedge of Cheese is unremarkable in any way, though it has a tendency to avoid notice, especially when food is being prepared.
There are no straight mechanical effects in a regular D&D game; the Wedge of Cheese instead brings about general prosperity on the domain of the owner. Livestock multiply, crops grow abundantly, trade deals are remarkably profitable. If the owner of the Cheese is a feudal landlord, his subjects also benefit from the same effect. (Should the DM wish there to be mechanical effects, particularly in a game with domain rules, absurdly high bonuses for growth and interaction are called for)
However, should the Cheese leave the owner's possession intact, the owner suffers a backlash from the ultimate loss of capital. His prosperity (and that of his subjects) plummets, as he suffers crop failure, his herds sicken and die, and his trade deals wither and die as bandits steal his caravans and he's cheated mercilessly by his partners.
The former owner will have a subconscious realization that the Cheese was there, and was the source of his fortune, and he will bend all his efforts to getting it back.
The Wedge of Cheese is quite tasty, too.
Brad