I've been trying to find the name of a movie. I saw it in the middle 1960's on TV in the US. It was in black and white. Pretty sure it was produced in the US. From what I remember of the clothes and whatnot, I suspect it was filmed in the 1950's.
A seemingly empty space ship landed near a small town. People started getting these disks on the back of their necks that were connected to the spine. If the disk got disturbed, the person died. The disk was about the size of a 50 cent piece and maybe a quarter inch thick. The people with the disks on the back of their necks were acting strangely and seemed to be under the control of others. At one point, one of the characters fired a revolver into an opening on the space ship and it echoed for a long time.