Which man from Saul's family cursed David and threw stones at him as he fled?

Answer: Shimei son of Gera

When Abishai offered to cut off Shimei's head, David said, "Leave him alone and let him curse me, for the LORD has told him so."

“As King David approached Bahurim, a man from the family of the house of Saul was just coming out. His name was Shimei son of Gera, and as he approached, he kept yelling out curses.”— 2 Samuel 16:5 (BSB)