Please be as detailed oriented as possible

2 Mary Poppins mows her own yard to save money. Her neighbor Paul George hired a lawn service to mow his yard. One day Mary was looking out the window and saw Paul's lawn service drive up and begin to mow her yard, not Paul's. Mary thinks that is great and does not say anything to the lawn service while they mow the yard. The following week, Mary gets a bill from the lawn service. She calls the owner and says that she does not have to pay because there was no contract by which she agreed to have her yard mowed. Is the lawn service entitled to payment by Mary? Why