Because of your Museum and blog, I've identified quite a few pencils that have come into my posession. I just identified another one that I *think* is a Selfeed: it's identical to the second pencil in your photo at http://www.jonathanveley.com/images/stories/pencils/s/selfeed.jpg except that it is entirely unmarked with name or patent or finish. From the look of it, it was never marked, though I suppose if the imprint was shallow enough, someone may have polished it off. There's no brassing, though, so I can't be certain ...
By the way, if you are researching Selfeeds, be sure to check out the article over at Leadhead's indexed under Selfeed about the wild goose chase several of us researchers went on to discover the real story behind these pencils.
Whether the unmarked examples come before or after the events in the Leadhead's article, I do not know.