- Charles Edward Parker, trading as the Parker Homestead Co.1
- Chester F. Cutler, Deep River, Iowa1
- Chicago & Northwestern Railway Co.1
- Citro Nesia Co. (Inc.)1
- Clara J. Berry, trading under the name of Berry's Golden Rule Poultry Farm, Clarinda, Iowa1
- Clarkson Gelatine Works1
- Clifton Drug Co.1
- Clinton Sugar Refining Company, of Clinton, Iowa1
- Coast Fishing Co.1
- Concentrated Products, Inc.1
- Conserva Di Poniidoro Vesuvian Preserving Co.1
- Council Bluffs Grape Growers' Association1
- D. Rothschild Grain Co1
- Davenport Vinegar & Pickling Works, a corporation, Davenport, Iowa1
- Des Moines Cooperative Dairy Marketing Association1
- Doud Milling Co.1
- Dr. Carey Medical Corporation, Rochester, N. Y.1
- Dr. J. A. McGill & Co.1
- Dr. LeGear Medicine Co.1
- Drovers Veterinary Union1