It depends on what you expect to bring to this plane. In the astral plane you, from what I gather from others, are a being of energy. You consciousness is in the astral plane while your physical body remains tethered to the earthly plane, so the things you encounter in the astral plane would also be things born of energy. What I mean is I know someone who is so good at energy manipulation they can, according to them, shape the energy into different forms but nobody save someone with similar skill would be able to touch or see these items. If you brought something back from a trip to the astral plane that item would still be energy and have no physical form on this plane.