Found some info:
"Polk C. Brockman, a young and imaginative Atlanta record dealer, conceived an idea of great consequence. He had grown up in a mercantile family and had entered his grandfather's furniture store,
James K. Polk, Inc., quickly taking over the phonograph department. By 1921 the firm was Okeh's largest regional outlet with particularly heavy sales of the new race records..."
http://www.lib.unc.edu/mss/sfc1/hillbilly/HTML/ArchieGreen/greenSection_02.htmSo Polk C Brockman was a record dealer, then got into the family furniture making business and I assume helped produce your phonograph.
"James K. Polk" is a song about James Knox Polk, the 11th president of the USA, but not the same person as the furniture store.
Also found: "In early June 1923, Polk C. Brockman, an Atlanta furniture store owner, who had been instrumental in the distribution of records for Okeh, went to New York to work out a new business deal with Okeh Records."
http://en.wikipedia.org/wiki/Fiddlin'_John_CarsonPolk C Brockman seems to have been involved in early country music and helped to further the career of Fiddlin' John Carson.
It seems he went on to scout more talent and start the careers of several musicians as their agent: "An Atlanta furniture dealer named Polk C. Brockman, who also served as New York's Okeh Records local talent scout and distributor persuaded the record label to come to Atlanta to record Fiddlin' John. "
http://ourgeorgiahistory.com/ogh/Fiddlin'_John_CarsonSo it seems your phonograph was made by his furniture store and he was the talent agent for several country music musicians. Hope that helps.