Random Mushrooms in Potting Soil??!

I purchased a couple of bags of Garden Club All-Purpose Potting Soil from Canadian Tire in Edmonton, and planted my orange mint plant in it. There are mushrooms growing out of it! The mushrooms seem a little spread out, I'd planted the orange mint plant from a 4" pot from a nursery, so I suspect that the soil was contaminated.

These mushrooms are small (just noticed them this morning, so they may be growing) and grey, with inverted caps. I got an okay picture: http://www.facebook.com/photo.php?pid=7286204&l=38f54caa4c&id=591965511

Anybody know what these are? I imagine if it's the wrong mushroom, the whole plant should be considered inedible. Should I throw the whole thing out? Are the spores going to fly around and poison me? I know, slightly paranoid...

 

I used to get those all the time with the Canadian Tire soil from Calgary Trail South; I don't know what they are, but they didn't seem to hurt my plants any, or me for that matter (although I didn't eat the shrooms, just the lettuce that was growing in the same spot.)

 

They are just the fruiting bodies of a fungus feeding on the ingredients in your potting soil, completely natural and they may even be in a symbiotic relationship with your plants; in what it called a Microrhyzal relationship. Nothing to worry about, just dont eat them. Spores are not poisonous, or we would all be dead thousands of years ago.