The minor league baseball team in Atlata (prior to the Braves moving there in 1964) was call the Atlanta Crackers.
The negro league baseball team in Atlanta was also called the Atlanta Crackers.
This is a reproduction of a 1939 Atlanta Crakcers baseball jersey:

In fact, you can buy Atlanta Crackers uniforms (both the minor league and negro league versions) all over the internet.
Cracker is about as much a slur as calling someone from NY a yankee. Yea, when someone from the south says yankee, they mean it negativly, but few people born up north would take it as an insult.
When people up north say cracker, they mean it as an insult, but few people form the south take it that way.

I wear mine to Astro’s games. That is when the humidy isn’t too bad. wool and humidity don’t go well. I’d just about kill for a green and gold Crackers warm up jacket. Kind the same colors as the Oakland A’s.