Cassiterite

Mind it won't be as spectacular as many people think such a discovery should be

I've got to disagree with you a little on this point, because even finding algae on other planets would be pretty damn spectacular!

I love this comic with that quote: http://zenpencils.com/wp-content/uploads/2012-04-04-edgar-mitchell.jpg (kinda large image)

His jokes are out of ha... godammit I'm not funny.

Devil's advocate: even supposing they were 100% legit, I think it's hard to argue that it would be unethical to send someone on a one way trip to Mars if that person wanted to do it.

You can definitely die if you eat enough, although it seems to be very rare, especially with modern medicine

The North American Mycological Association has stated that there were: "no reliably documented cases of death from toxins in these mushrooms in the past 100 years". -Wikipedia

Doubt it's worth it though, apparently the trip isn't even fun.