Where did the good ole boy come up with Ricin?
Is he just a pest who wrote one too many letters?
They sure got him quick, didn’t they?
It's from Castor Beans. One of the most trivial deadly substances to produce. You don't exactly need a chemical weapons lab and a PhD. It's actually more complicated to make Meth and plenty of Good 'ol Boys do that.
Though as another poster mentioned I would not be surprised that further testing reveals it's not actually Ricin - testing for it accurately is much harder than making it, and there are a lot of false positives.