One day they find and feast on lettuces that have shot into flower, and, under their "soporific" influence, fall asleep in the rubbish heap, though Benjamin puts a sack over his head. Mr. McGregor discovers them by accident when tipping grass-clippings down and places them in a sack and ties it shut then sets the sack aside while attending to another matter. Benjamin and Flopsy are unable to help their children, but a "resourceful" wood mouse called Thomasina Tittlemouse, gnaws a hole in the sack and the bunnies escape. Their parents fill the sack with rotten vegetables, and the animals hide under a bush to observe Mr. McGregor's reaction.