There are several places in Atlanta where you can get bread without packaging. Here's the thing, you have to call in the morning explain your zero waste lifestyle and ask them to set aside a loaf for you unpackaged. Top choices for zero waste bread are La Calavera Bakery (Decatur), Highland Bakery (Old 4th Ward), Alon's (Virginia Highland/ Dunwoody) and newly-opened Proof (Inman Park).
Also if you're lucky, you can sometimes get zero waste bread at Whole Foods if they have some unpackaged loaves in the bakery.