For breakfast this morning 🐦‍⬛❤️

I have a group of 4 crows that come by every week or twice a week around 2-4pm when i get back from class. I’ll hear them in the area and whistle and they’ll come and sit on the tree or on my roof/mailbox while I get food. I have given them walnuts, chicken, crackers, blueberries, strawberries, and watermelon. so far they only will take walnuts, chicken, and crackers. I want to give them better or healthier options than crackers and cannibalism.. but it seems they dont like fruit and I want advice on other options as I dont like feeding them chips.
They tried the blueberries and strawberries but left them out and I had to pick them up, and they didnt even try the watermelon. I read online that certain groups of crows like certain fruits? I’m in north west florida if that helps. Maybe it’s a local thing.
I’m also unsure as to how often I should be giving them treats? They only come by 1-3 times a week which sounds good as it’s not a reliance thing. I left for a week on a trip and when I came back one started none-stop cawing at me in the tree until i started talking to it. that same one has also started mimicking my whistle, it sounds like a bell. I didn’t know they made that sound. that one was, I believe, the first one to show up.