Crows are a fascinating sect of birds. A whole group of crows is not called a flock, but a "murder". There is a crow that comes to my yard daily and hangs out. I throw him scrambled eggs, or whatever is on my breakfast plate. He seems pretty comfortable with me, and I will see him now several times a day. He even flies down to see me at other points in the day. So, me being me, I had to read on crows.
Crows are unique in the sense that they recognize faces on people. They remember when someone has been kind to them or unkind. Sometimes they can hold a grudge even. Crows also let the rest of the murder know what kind of human you are. The whole murder may act friendly or hostile towards you depending on what they have been told. Gossipy little things right? They are probably the most intelligent bird of all birds. They have also been known to leave little gifts (shiny trinkets) for those they care for.