As tipped here first, John Legend indeed was a special guest at the big fundraiser his “Glory” Oscar-winning songwriting partner Common, held for his Common Ground Foundation Saturday at Perillo Rolls-Royce/Bentley dealership on the Gold Coast. Among the posh crowd on hand for the fete were Mayor Rahm Emanuel and his wife, Amy Rule, Les Coney, Matt Forte, the Rev. Michael Pfleger and (natch!) Joe Perillo. … While back in his hometown, Common also was spied noshing at the Local Chicago at Delaware and Mies van der Rohe. … Lauren Conrad slipped into RL Saturday for dinner with a couple of girlfriends. … Former Chicago Park District superintendent Ed Kelly and wife Marilyn joined Rasheda and Jamillah Ali, the daughters of Muhammed Ali, for lunch at O’Brien’s Restaurant on Wells Street in Old Town. During their meal, Ali’s daughters got “The Greatest” on the phone, much to the delight of all concerned. … Congrats to Ravinia CEO Welz Kauffman, who was at New York’s 42 West to help celebrate the upcoming DVD release Tuesday of the “Into The Woods” film, based on composer Stephen Sondheim’s musical. The Sunday fete also toasted Sondheim’s 85th birthday — with such artists as Billy Magnussen, MacKenzie Mauzy and Rufus Wainwright on hand. … Another weekend sighting was the Backstreet Boys — including A.J. McLean, Howie Dorough and Nick Carter — dining at Chicago Cut Steakhouse on the river, while the bandmates were in town for America’s Beauty Show at McCormick Place.