I found this on some website:
I can tell you that Parson Brown was a pastor in Florida who developed the Parson Brown Orange around 1856. And FYI, the Parson Brown is an early season orange that can be harvested slightly earlier than the Hamlin. It is described as rough-skinned, with pale juice; moderately seedy; of low-to-medium quality. Originally grown in Florida it is now found mainly in Texas, Arizona and Louisiana.