You won’t usually find Alice Walton’s name listed among America’s more prominent art collectors, but the WalMart heiress has spent the last 15 years amassing an impressive array of American art. “Slowly and methodically, Ms. Walton has paid top dollar at auction and through dealers for the best paintings, drawings and sculptures she can find by artists like Winslow Homer, Edward Hopper, George Bellows, Marsden Hartley and Charles Willson Peale. The goal, the family foundation says, is to start a museum in Bentonville, Ark., where her father, Sam Walton, opened his first retail store in 1951.”