They owned many milk vending machines across the streets, as well as at least one creamery, which provided milk for the Medford area.
Little Cobb Creamery is mentioned only in Fallout 4.
↑Fallout 4 Vault Dweller's Survival Guide Collector's Edition p. 276: "[2.06] PARSONS CREAMERY This company once provided milk for the Medford area and was part of the Little Cobb Creamery collective. Unless the specified quest is active, this place is deserted. Otherwise, expect a Raider presence. If you're adept at safecracking, expect a pleasant surprise here (Advanced). Explore the roof to locate a skeleton close to an assault rifle and locked wooden crate (Novice). If you're after a boatload of grenades, you've come to the right place." (Fallout 4 Vault Dweller's Survival Guide Map)