Every Friday from 6-9p.m. the Whitney Museum has a pay-as-you-wish window. I wish for unicorns. But like money, I haven’t any. Instead I get an amazing and free glimpse into one of the largest one-time collections and the only U.S. retrospective of the great photographer, William Eggleston. The show runs through January 25 and includes not only nearly all his black and white and color prints from over 40 years, but also his films from the 1970s. Go see some Americana before we mortgage it to China.