I don't really know what to fill pin cushions with. I don't use walnut shells in mine. My DD is allergic to tree nuts and could react from touching my pin cushion. I have one that was a gift that has walnut shells and it is only used as a decoration. If you do fill them with walnut shell you should let others know. I had never heard of putting walnut shells in a pin cushion when I got the elephant one as a gift.