I toss mine out into the lawn and shred them with the lawnmower. Some of them will actually survive that abuse and root down and start growing in amongst the grass. They eventually disappear though, apparently getting mowed off every week is more than they can tolerate over the long term.
I've been told you shouldn't give away irises that aren't good enough to register. One problem I can see is that you give a seedling to someone, they pass it around to their friends and so on, a few years later someone posts a picture of it online saying 'What it's name?', a well meaning person suggests a similar named variety, and pretty soon the unnamed seedling is being passed around under the wrong name. Obviously, the world won't end if something like that happens. But, out of respect for the work real hybridizers do, I choose to not give away seedlings.
