Your uncle clearly misappropriated property not belonging to him.
By accepting it as a gift, you are now an accessory to the fact.
Old friend of yours is asking you to participate in destruction of property, doesn't matter how small or valueless it seems it's not yours to keep discard or destroy... You should be trying to find the rightful owner and returning said item.
These things while seemingly insignificant hold great value and meaning to their owners. I know this cause I'm a jeweller and I've had customers tell me how precious their jewellery can be.