I have always just thrown most of these away, giving some little pieces to my dog as I trim (she has been taught to stay out of the kitchen, but can spot a brisket coming in every time) I have known people who trim then lay the trimmings back on top of the brisket while cooking. Now I hear of saving/freezing and using for stock or gravy and the like. what do you do? how do you use it for stock? just put chunks in a hot pan? the hard chunks of fat or the softer ones?