The Manhole Cover Patch

During the August 1957 "Pascal-B" underground nuclear test (Operation Plumbbob), a 900-kilogram (2,000 lbs) steel cap was launched into the atmosphere at high speed after a 50,000-fold higher than expected explosion. Dr. Robert Brownlee estimated it exceeded escape velocity 67 km/s or 150,000 mph, with scientists suggesting it likely vaporized from compression heating, though it may have escaped Earth.

Personally, I believe it is the first manmade object in space. Take that, Sputnik.