This is a great old blues song, and the Richard "Rabbit" Brown record is fantastic. He's an interesting figure; if I recall correctly, not much is known about him, and he only made a few recordings. His sound and his diction are very distinct. Perhaps the recording, and his accent, are factors, but he shifts between being clearly understandable and difficult to make out.(His voice sometimes reminds me of Cat Stevens, of all people.)
In listening back to the original record, the lyrics posted above are basically correct, but are not an exact transcription of Brown's recording. I think the biggest difference is that he seems to be saying:
"I been givin' you sugar for sugar, let you get salt for salt.
I('ll) give you sugar for sugar, let you get salt for salt."

Also, I always thought it was:
"Cause I was born in the country she thinks I'm easy to rule.",
but listening back, maybe it's "lose". I like "rule", though.

Another: I think it starts with:
"Times (they?) ain't now nothing like they used to be", which seems a more poetic rearranging of the words.

Agreed with catyronwode above re no "ain't" in that stanza. It's:
"I done seen better days, but I'm puttin' up with these".

There are other small variations.

Thanks, all!