Flour is in short supply in many food stores as many Americans looking for ways to entertain themselves or learn new skills while they remain at home are baking. Hometown Food Company, which owns Arrowhead Mills, Lily, Martha White and Pillsbury flour brands, said it first began to see sales pick up in March and then accelerate. “We are making the flour as fast as we possibly can and shipping it to our customers, and it’s flying off the shelves as soon as it gets there,” said Brent Minner, a marketing director for Hometown.