Neil Armstrong & Buzz Aldrin left a variety of objects on the moon. Included among these was Yuri Gagarin’s cosmonaut medal.
Apollo 12 crashed a 2.5 ton empty Lunar Module onto the moon. The moon then rang like a bell for an hour, hinting at very strange underground structures.
There are 160 missing moon rocks from the Apollo 11 & 17 missions. 0.2g of lunar dust was bought for $442,000 [£280,800].