Be careful throwing them whole bread slices. They'll try to shove it down, and can choke. I always crumble any bread into small crumbs. Or anything else I feed them, unless it's something hard that they
I also feed leftover bread broken into pieces. I have also given them the crusts from my kids' PB&J sandwiches and they totally dig it! My guess is that peanut butter, like everything else given as a treat in moderation, is okay.