You're probably right. And no, Cassus wasn't a farmer. But Fett, or Vhett, does mean "farmer" in Mando'a. (See Bloodlines, Ch. 6 page 121, second paragraph past the dialoge.) Yes I'm such a geek I looked it up! LOL!
I sat in on a Fett panel at CIII and there were all kinds of ideas and theories tossed around about all things Fett. It was really interesting to hear all the ideas and opinions. The wheat symbol was discussed, but I have to admit by that point I was going on caffiene and about 3 hrs of sleep! LOL!
I figure it will eventually be fully explained in a future book.