Iowa was not the only state with a button industry. In Lamont, Michigan, west of Grand Rapids, there was also a factory. The town is tiny now--not even a grocery store. The factory was near where the town nursing home is now. We went there a few summers ago and found a shell with holes in it and some of the mistake buttons like those mentioned by idesofmarch. I hope to go back someday and find more artifacts. Button manufacturing is a fascinating part of business history to which more serious scholarly attention should be paid.