In an 8x8x2-inch or 9x9x2-inch baking pan or disposable foil pan, combine the mushrooms, butter or margarine, and bouillon granules.
In a covered grill, arrange medium-hot coals to one side of the grill for indirect cooking. Test for medium heat where mushrooms will cook.
Place pan of mushrooms, uncovered, on the grill rack (not over the coals). Sprinkle some of the soaked wood chips over the coals. Cover and grill for 45 to 60 minutes, stirring mushrooms and adding additional wood chips occasionally. Makes 4 to 6 side-dish servings.