This was about 40 years ago, we were camping in the summer in the woods behind a friend's house.
About 11:00 p.m., we had to walk back to the house for something.
It was a full Moon, and there was plenty of light so we didn't take flashlights.
We went out of the woods and down a long lane that went along an open pasture between the woods and the house.
We got what we needed and started to walk back.
The Moon was behind us over our right shoulder.
We could see our shadows on the ground ahead of us from the Moon.
As we were walking we saw a black circle with no lights.
It just looked like a black hole in the sky.
It was very low above the trees and moving towards us slowly.
We all stopped, 4 of us, and watched it.
It came over the trees and over the pasture, and then you could see a shadow moving on the ground where the moonlight was giving the thing a shadow just like us.
And it went from northwest to southeast and passed over us and kept going until we couldn't see it anymore.
It lasted about 2 minutes.
It did not make any noise.
It did not look like anything, just a perfectly round black circle.
It had no lights and moonlight did not reflect off it.
It made a shadow that was about the size of a house.
I don't know how high it was because it had no detail but it seemed very low, like a couple of hundred feet.
We told our parents the next day, but no one believed us.