Ann Decherd said she had “tears of joy” in her eyes Saturday morning. The branch manager of the new Post Road library, Decherd was thrilled with the turnout for the grand opening of the 23,500-square-foot facility in west Forsyth. “I’m not sure exactly how many people we’ve had come through so far,” she said about two hours after the branch opened at 10 a.m. “But I know we had more than 180 kids alone take part in our first story time with Tacky the Penguin.