I have tried feeding our 4 Khakis and 2 Magpies produce (lettuce, cauliflower, leafy greens, cabbage) and they seem to prefer dandelions and to bypass the produce. Is this common? Also, does anyone know of a list of foods/weeds that are poisonous to ducks? I know tomato/potato/rhubarb plants are poisonous, and that buttercup is supposedly toxic, but is there a reference for such things. Haven't been able to find such information on searches on the internet. We have butter cup all over our yard where the ducks forage....they seem to stay away from it, but it concerns me.