Not exactly bushtucker, but thought it would be interesting. A mate opened some packets of Kookaburra brand white rice the other day, which according to the packets went use by in early 2009(!). These were part of some old cyclone stocks that had been sealed by him and forgotten for 10 years.
Looked good, and apparently tasted good when cooked, turned out to be fine. I know brown rice lasts shorter time than white but prior to this I had been told 2-3 years is about the limit for white before it becomes rancid. Maybe rice lasting longer is common knowledge to everyone else, but I was quite surprised.