- Old Exchange and Provost Dungeon Museum, Charleston, S.C.1
- Oleomargarine1
- Omega1
- Oriental1
- P. Co., Inc.1
- Parkay;Kraft Cheese Company1
- Parowax1
- Penick & Ford Ltd., Incorporated1
- Perfection Stove Company1
- Pet Milk Co.1
- Philadelphia Inter-State Dairy Council, Philadelphia, Pennsylvania1
- Piggly Wiggly Bird Co.1
- Pillsbury Flour Mills Co.1
- Pillsbury Food Products, Minneapolis, Minnesota1
- Pillsbury Home Service Center1
- Pillsbury Mills, Inc.1
- Plant Flour Mills Co., St. Louis, Missouri1
- Planters1
- Plymouth Rock, New York
1
- Portable Kitchens Division of Hamlin Products, Inc.1