This is a mini needle magnet, a little smaller than a dime. A pewter clad with a strong earth magnet, this will hold needles or scissors in place. You get two for the price of one, the pictures show the opposite side of the minder with the button on top.
Needle minders have become one of the most useful items in your tool box. You’ll find many applications for them as decorations for scarves, coat lapels, etc.