Good question. Traditional bread can be around 15g of carbs or more per slice.
There are lots of alternatives to bread such as Flatout Light wraps that only have 6g of net carbs. However, if you want real bread you're going to have to hunt. If you're ok with ordering online, Julian Bakery specializes in low carb bread. It's pretty good stuff at only 1g net carb a slice. However, it's quite expensive. Plus, you have to pay for shipping.