During Apollo 11, the first manned lunar landing, a "contingency sample" was taken by Neil Armstrong. From Wikipedia:
About seven minutes after stepping onto the Moon's surface, Armstrong collected a contingency soil sample using a sample bag on a stick. He then folded the bag and tucked it into a pocket on his right thigh. This was to guarantee there would be some lunar soil brought back in case an emergency required the astronauts to abandon the EVA and return to the LM
Where is this sample currently located?