Last summer I made an attempt at befriending a crow. It actually went pretty well, but the treasures that he brought me blew my mind:
* French fries
* Cooked pasta, maybe baked ziti?
* BBQ ribs, but just the bone with some sauce on it
* Chicken nuggets
* One dead bird, conveniently opened for me
* Several whole dead baby chicks
* One baby chick's head
I stopped feeding it after it kept leaving us, and my neighbor, the dead birds, and it was fowling (ha) up the water in her bird bath. It loved blueberries, cat food, pepitas, and walnuts. It did not like apples and would toss them aside.
I would shake my car keys when I put the food out, and it would show up a few minutes later, but I never figured out if it just saw me or heard the keys.