I'm agreeing with you... Chickens seem to have a natural sense of what's good food found in the pasture, BUT when it comes to inanimate objects such as screws, wire, insulation, etc they somehow feel the need to try it. I don't get it but I don't worry about the selection of plants they want to eat from. I'd really like it if they'd quit eating my tomatillos, just a day or so before they are ripe.Beans have toxins in them. Cooked can be offered. Chickens very seldom will choose to eat things that are bad for them. With that being said I’ve seen them go after insulation foam....sometimes they are not the brightest crayon in the box.