Drain cans of yams. Place into a large casserole dish. Pour in the can of pineapple (use more or less to your liking) juice & bits. Sprinkle the brown sugar on top. Mix all together gently (the yams will be soft). Sprinkle on the marshmallows on top. Bake at 375 for 15 minutes and broil for 2 just to get the marshmallows browned.