MINNEAPOLIS — The Minnesota Historical Society has added a podcast at discussions.mnhs.org/collections that describes the processing of Richard Ferrell’s flour milling industry history collection. It is the third podcast of the collection to be developed by the M.H.S., which acquired a significant portion of the collection in 2007. For 40 years Mr. Ferrell, who once managed Pillsbury’s historic ‘A’ Mill on Minneapolis’s east bank, collected flour milling objects, photos, advertisements and memorabilia. The collection represents the industry’s development from the mid-1800s to the present through more than 3,000 different objects, including flour bags, barrels, advertising broadsides, company premiums, trade journals, photos and postcards showing mills throughout the region.