Are fresh, raw cashews different from store-bought? I have a pen pal in Brazil (is it still a pen pal if we e-mail? anyway...) and knowing that I like nuts sent me some cashews.  Apparently there is a cashew farm near enough to her that she went right to the source and procured me some raw nuts.  I've eaten a few handfuls; the taste is a little more sharp than I'm used to, but in a good way, I have however had some serious discomfort after eating them. I'm not allergic to nuts in general or cashews specifically so I thought I would ask about it before ingesting any more.  Anybody have any ideas or thoughts?
Nuts can go rancid. I've also had stale nuts, pecans or peanuts that were exposed to too much humidity. This adversely affects the texture. They need to be fresher than that.

Cashews, however, are in a slightly different boat. See Anacardium occidentale L.

Cashews have a toxin in their shells that resembles poison ivy. When harvested, cashews are roasted in their shells to reduce the toxin and make the shells brittle and easy to remove.

If these cashews were harvested by an amateur this process might have not been done correctly and you may be reacting to the toxin.