These are the crows I feed in the park. This pair are usually waiting for me and they make a racket in the trees when they see me walk past! I know its the same pair because the one on the right has 2 white tail feathers. Ocasionally another crow tries to muscle in but they chase it off. I feed them meal worm which is nice and light to carry in my handbag :-) They fly down immediately after I put the food down and are getting cheekier all the time. One day after I fed them they flew after me and made a racket so I gave them a second helping.
I remember reading an article in the RSPB Membership magazine and it said that if you see two crows together they are usually a lifelong pair, if you see three its probably parents and their offspring (you usually notice that one of the crows is smaller and scruffier looking), more than three - are the crows who have not found a mate yet, non-breeding crows. So these two must be a lifelong pair. I've noticed that they also take turns in acting as a look-out while one feeds.