NPR : Mustard Plants to Boldly Grow Where…
NPR.org, July 24, 2006
On board the space shuttle that lifted off July 4 was a black plastic briefcase marked "critical Space Item." Inside were 600 seeds.
(Full story at link)
When I save my seeds I put them in those little 2x3 baggies the briefcase sounds a little like overkill to me. And trading seeds with people in Canada seems hard enough I can't imagine trading with someone in space. :-)