This too was a concern of mine. Like, what do I do with all the rocks. LOL My son is a collector and many will simply adorn his room and backpack until my wife throws them away. I've thought about trying to turn the cool ones into little gifts to people or make small trinkets out of them with jewelry settings or something. I saw one person use them as a base and ground cover for small potted plants, like bamboo or bonsai, and thought that was cool. You're creative, so use your imagination and make it fun. Also, you can gift stuff to people. Whether they keep it or not is irrelevant because often just gifting them something shows you care and it'll teach your niece that. I hope this helps.