What about fresh Bing cherries and blueberries? Ziggy adores both and has never gotten sick. I know you have to be careful not to let them eat the cherry pit as it contains cyanide.

This includes peach pits and apricot pits as well.
Also, was baby food mentioned yet? A lot of it is bad because it is seasoned with onion powder or onion salt. I think everyone knows that anything onion is bad.