I have a pattern for a tea cup pin cushion:
http://www.sew-whats-new.com/projects/t-cup-pin-C.shtml
They recommend steel wool. My tip would be "do not use polyester." You know how it dulls your rotary cutter blades when you cut it. If you are going to put needles in this pin cushion, you want something that will sharpen, noto dull them.
Now, take a look at what is in the old fashioned pin cushions. The little strawberry is filled with sand, but the "tomato" is filled with something akin to sawdust.
Perhaps some of you will use this pattern. I have been collecting cups and saucers from Thrift stores and plan to make some for gifts. You can be creative and use other things like antique sugar bowls, creamers, etc.
I do hope this is helpful to someone.
June in Cincinnati