I'd been trying to attract crows for several months by offering them roasted, unsalted peanuts in the shell. Got blue jays, red-bellied woodpecker, titmice, grackles, but no crows. On the advice of a friend, I switched to dog kibble (Purina Dog Chow). Bingo. Crows love it, and yesterday a crow was at the feeder less than thirty seconds after I'd refilled it and walked away. Four days in a row, I'm reliably getting crows. (Note: unlike peanuts, dog kibble is NOT waterproof, and makes a soggy mess if it gets wet).