i have heard about it while in china. it is called a " yard sale ". i didn't have any idea of that until today when i came here to the big " yard sale ".
it's wise to do it. the americans have the habit of selling their junk when they are moving to another place, so they usually display all the things they want to sell in their gardens at the weekend. and many things they are selling still look quite new and they are also very useful.