Corvids are smart and have some kind of active shared education, so they're always quite skittish around humans. I suspect (with no evidence or research) that they sense the cultural enmity humans have, and possibly remember the long history of "pest control" (which still happens on farms). They'll eventually learn that you're a cool human.

One way I feed them is to show them the food, then place it somewhere visible like on a post or stump, and back away to let them choose to take it. Throwing motions startle them pretty easily, even when they're very gentle.