metal trash bin. you can find these at your local hardware store. if you have a raccoon/opossum problem as well you can bungee the lids closed to keep them out. a large heavy rock works pretty well too!
be careful not to spill food when you’re filling the chicken feeders because that will attract the rats right to the source. i know this is easier said than done. i know that we are all taught to keep a constant supply of food available for the chickens. if this constant supply is not kept inside a rat-proof coop at all times (and who has one of these?) then you're going to have 