As a general rule crows are wild animals so don’t try capturing them, let them fly free. If a crow wants to come near you let it be its decision, don’t try chasing after them. If you find a wounded crow find a wildlife rehabilitator or contact a veterinarian.
If you rent a place or live somewhere temporarily (about 3 years) don’t befriend them, they can live up to 17 years. Go to a park at the same time every day so that you and the crows form a routine and a relationship.
A good thing to feed them is natural nuts in a shell, it prevents the smaller birds from being interested but the crows are intelligent enough to break trough the shell to be interested. A good time to feed them is the morning or afternoon, when they are on the lookout for food.
I’d myself go with hazelnut and pistachios, because I’ve found them at the shop, but peanuts are also good.