I had a pet Jackdow (smuggled from russia where my parents saved it when it was a baby and fell out of the next and couldn't fly away with the flock). we also had a pet starling we rescued in NYC.
these kinds of birds are not seed-eaters but eat both seeds and insects, so regular pet-food is no good for them. We made a mix of egg yolk (hard boiled) bread crumbs, egg shell ground to pouder, and bird vitamins. into this we added whatever we were eating, ground, such as veggies or grount chicken or beef. We also fed it insects we caught in the summer or any fly we caught inside the house.
besides the fact that you may get in trouble with the law, can't really BUY one, and have to make your own food for it... i don't see much of a problem. You should probably know a little about birds before you get any bird, and 100% you should read a book about parrots (a pet owner's manual, etc) from amazon or your library before getting any bird. i don't know how you can "get" a raven, and i am NOT advocating that you capture one, but if you find a CROW that's injured or something... why not?