Here are two plastic buttons with plastic coated wire wound around to make a pattern. The white one has green wire and is a sew through type. The black one is more intricately wound in two oval shapes and just goes around to the back. It has no shank and you have to sew through the wire at the back. I think they may be from after the 2nd world war when materials were not so plentiful. They are quite different and in some ways striking. They measure 3 cm.