Strangely enough, it's called a U-Type nut!!!
See:
http://www.allmetalssupply.com/u_type_nuts.htm

--
73, Paul (N0KIA)


Alan P. Biddle wrote:

Joe,

Go to a hardware store and ask. I can't remember the same, but there
is a commercial product, usually hanging on a peg at the end of an
isle, which looks like some small strips of aluminum foil. You push
one, or more, into the hole, insert the screw, and tear off the
excess. It molds itself to the hole and does not easily fall out,
though you can remove it if you want. I have used it for what you
want, and at least for me it worked fine. Works on much larger screws
as well.



--
Alan
WA4SCA