Unlike most banks abroad, most American banks in smaller centers don’t keep foreign currency on hand. You can’t just waltz up and buy a couple hundred euros, pounds, Canadian dollars or Mexican pesos. (Personally, I think this is just wrong, but I am one mere mortal among minions.)
If you need foreign currency prior to departure for adventures abroad, you need to order from your bank well in advance. And you’d better check which specific branch will handle it. Most bank branches outside of those near UAB in Birmingham’s downtown (and a limited selection in Mountain Brook – Brookies, you are well served.) don’t deal with foreign currency at all. For most travellers, using the foreign exchange outlet of one of larger international airports on their way overseas is the easiest option.