Mary (Buoy) Lee, the founder and matriarch of the Harvard Square landmark Hong Kong Chinese restaurant, a favorite haunt of students and locals alike for more than six decades, died on Aug. 17 in Cambridge. She was 90. Lee died of a stroke, according to Paul Lee, her oldest son and the restaurant’s manager. In honor of Lee’s passing, the Kong, as the restaurant is affectionately known among Harvard students, closed on Aug. 25, the day of her burial.