We recently purchased a winter trailer in Arizona and want to take down some patio furniture,household utensils and linens etc. what is the expectation at the usa boarder.

Going into Mexico? Not a real problem on the US side if properly titled and tagged. Not sure about Mexico, they will inspect but should not be an issue. Are you planning to leave it in Mexico? Contents as household items typically have a duty 5%? And you need a form-FM3?