Clean Hands Version: Buy local specialties (such as refrigerator magnets, tobacco and alcohol snacks, etc.) at your destination.
Small Hands Version: Collect a few scenic rocks (currently, I have rocks from the Yellow River and from Dongzhou Island in Shandong), if there are lakes or seas in the scenic area, bring back a bottle of water using a mineral water bottle (currently, I have water from the Yellow River and from Inner Mongolia's Milk Lake).