Seems like a good way to grant the party a bag of holding early on. They just come across it discarded in a corner somewhere, and are stunned that an item in such good shape was just abandoned. It appears brand new and has a mix of mundane objects and apparent treasures inside, and the words “Bran’s Bag of Holding” is stitched in elegant lettering on the outside. If they try to dump it out to do an inventory, one random object remains inside. It takes a very high skill check to notice this, as the mimic mimics the inside of the bag as it holds on. If they dump the bag out a second time, the assortment of objects is the same except for a single item. Asking around reveals that Bran was a famous local adventurer who disappeared suddenly.