Michigan had several clay sewer tile factories, and like the others (particularly in Ohio) their workers would take unused clay at the end of the day and make whimsical pieces of pottery for friends. This sewer tile head (with a pile of tiles stacked ready for transport in the Real Photo Postcard) is signed on the base Curtis Rugge who was a pretty good sculptor. See also the essay by Marsha MacDowell and Kurt Dewhurst from 1980 titled The Sewer Tile Clay Pottery of Grand Ledge, Michigan. Interestingly, they point out that Michigan drew employees from Ohio to work for them...a small rivalry, but likely also an exchange of skills and ideas for pieces like this.
Grand Ledge folk art Sewer Tile Head and Real Photo Postcard collection Jim Linderman