The list is long, and many are the legends, for there is scarce a noble house in all the Reach that does not boast of descent from one of Garth Greenhand’s countless children. Even the heroes of other lands and kingdoms are sometimes numbered amongst the offspring of the Greenhand.
I know that Mary’s covering up her involvement with the British Men of Letters in this specific scene, but it does feel like her approach to hunting is different to John’s, and by extension Sam and Dean’s. She sets out to build networks and alliances with other hunters (which feels like it’s a more common approach?), whereas John burned bridges with Ellen and Bobby, two of the few other hunters he interacted with, and seems to have raised his sons with the expectation that they would hunt mostly by themselves.