My brother got to know a man who was a P-51 pilot during and after WWII. He name was Charlie and he apparently was with the 357th FG, since Chuck Yeager was a personal friend of his. One day in 1944, probably before 6 Jun 1944, his unit was performing a fighter sweep over France ahead of a B-17 bombing raid. They ran into some FW-190's and a few BF-109's. A large furball of a dogfight developed and as so often happened he found himself alone, headed east, approaching the border between France and Germany. He looked down and was very surprised to see what he could identify as an Me-262. He had never seen one before but they had been briefed on them. He had a huge altitude advantage and figured this was a chance to nail one of the new German jets. He gave his Mustang full power and dove on the Me-262. On the way down he noted that the 262 was not the only airplane down below. Ahead of the German jet was what had to be another German jet, and unlike the 262 it was shiny and unpainted. Both were traveling at very high speed. Charlie figured he had really hit the jackpot. He had a chance to not only shoot down an Me-262 but also some other kind of experimental German aircraft that the 262 presumably was escorting. At full power in the dive he was just barely closing on the 262 when suddenly the shiny aircraft accelerated incredibly quickly to unbelievable speed and simply disappeared from sight. Charlie was stunned. He pulled out of the dive and pulled back on his throttle, all while staring at the point where the shiny thing had disappeared. And then he realized he was flying formation with the Me-262, whose pilot clearly had pulled back on his power, too. The German looked over at Charlie with a stunned expression on his face, and threw both of his hands up, in a gesture that undoubtedly said "What the .... was that?" Charlie repeated the same gesture to the German, tossed him a salute, and did a quick 180 for home. And yes, the silver aircraft was indeed disk shaped.