To post anywhere you need to dig a hole 3 or 4 feet deep and put in a 4x4 treated piece of lumber. Put some dry concrete in the hole and give it a day or two to let the ground moisture firm it up. Then you can put up a sign or whatever you want on the post. I'd recommend the Gadsten flag with the snake (the first American flag) which says 'Don't Tread On Me'.