St. Margaret’s Episcopal Church will celebrate its 90th anniversary with a community social. From 2 to 4 p.m. Saturday, May 14, the church and its grounds at the corner of Court and Elm streets will turn the clock back to May 1915, when ground was broken for a “summer chapel,” designed by Boston architect R.W. Porter to be similar to a chapel in Salisbury, England. Women are invited to wear elegant hats from the era, with a prize awaiting the most beautiful vintage hat. Free lemonade and ice cream cones will be served while children try their skills at games that were popular almost a century ago. Inside the church, Ron and Carol Whittle, in period costume, will tell the story of St. Margaret’s beginnings.