Yep.
Use a plain brown box (or have any logos or old shipping material marked over - I use black spray paint) and a printed out shipping label paid for over the net securely attached with clear tape.
Walk in to shipping point of choice, lay package on counter and say in a cheerful voice, "this is ready to go!". Clerk says "thanks!", then I walk out and everyone is happy. At USPS they will ask if it is liquid, fragile, perishable or potentially hazardous or contains lithium batteries, to which I reply "nope" then I walk out and everyone is happy. At least that's how it's gone when using UPS, FedEx and USPS at several different shipping points.
