Jingszo !

Sorry, I should have been more clear; the Me 163 was capable of 1200 mph (I think the highest recorded speed was 1300mph, but the pilot spectacularly didn't survive) and we don't talk about it because it was used by the Nazis to break the sound barrier.

And I am also sorry to say, you're just incorrect about the technology at the time. The V2 topped out at over 3000 mph, for example.

In 1947 the Soviet Union launched its first V-2 assembled from German parts.

To think that the US, who acquired far more of the scientists from the Nazi rocket program than the soviet union (who just got the spare parts), was behind them at this point in time is pretty goofy. Do I know what the wreckage was? No, and I wouldn't be allowed to talk about it if I did. But given the sheer amount of cartoonish nonsense the US was attempting at the time, it's not unreasonable for that wreckage to have been anything from the Mogul balloons, an Me163-derived experimental craft, some kind of supersonic blimp (no, that was a real thing. Though as far as I'm aware they never got them off the ground.), targets for high altitude interceptor missiles (that obviously didn't really work yet, but Artemis was started in 1943), a big rock with a tunnel painted on the side, to any other one of a thousand speculative guesses that get less and less likely.

All of these examples would have contained foil, rubber, sticks and whatever 'durable paper' actually means (the best theories I have heard are that it was the precursor to ripstop nylon, or an early mylar or metalized film, which were both being considered for high-altitude, high-speed parachutes at the time.) But really, there are nowhere near enough details to do more than speculate wildly on what it might have been. It's like asking what color dinosaurs were - there's so little information available to us that any answer has an equal likelihood of being the correct answer.