I've tried to befriend some crows in the local park a while ago and it worked fairly well. I gave them some peanuts about twice a week and they soon started to recognize and gather around me. Sometimes some of them even jumped on the bench I was sitting on. I stopped feeding them because there where just too many of them (about 15) and it was a bit much for me. But recently I've spotted a crow couple in the area. Maybe I will try to befriend them with some treats.