What kind ok clip is this?
 

These are used liberally on my 27 T Coupe. There is a row on the panel above the windshield and several around the doors and windows. I believe they are used to secure the upholstery and trim screws. I need to find a bunch of them anyone know what they are called and where they may be obtainable? they fit in 3/8-inch round holes. Thanks for any hints. I have enclosed a couple of photos to show what they look like. I have searched most of the T suppliers and a few A suppliers to no avail.