Yes, you can have a US mail address which you can use to do your shopping in the USA.
The forwarding service that you will sign up with will ship packages or mail to you (some of them anywhere in the world!) for a small fee. Not all forwarding companies ship packages, some of them forward only letters. Some forwarding companies will even do the shopping for you! Some will even deposit your checks to your bank! Search here for letter- and package-forwarding companies in the USA.