"London hugged and kissed her saying, 'Baby ... mine!'" McDonough tells PEOPLE.
Son Morgan suggested the baby's name, which was inspired by the four-leaf clover. "It has four leaves and this is our fourth child. Clover signifies good luck – I'm Irish and Ruvé's favorite color is green," the actor explains.
Clover was born at Good Samaritan Hospital, where McDonough serves as celebrity chairperson. "It's a wonderful, amazing hospital," he says. "All of our children have been born there."