BYOB's are against the law in MD, if the restaurant has a license to sell wine. If the restaurant has no license and doesn't sell alcohol, then they typically will permit you to bring your own. But, then, most of those places aren't so great.
One place is in Towson, called the Orchard Market Place. Owned by Iranians, it has very good Persian food. The service is on the slow side. You certainly need a reservation as it is usually full.