Well, I had to do a little research on the question of the mushrooms, but I'm not sure if I can pass the gumshoe level to double agent superstar. I have to admit, I'm still a tad confused. It seems that all these mushrooms under discussion are all varieties/strains of, if I may lapse into Latin, agaricus bisporus. Don't call your momz that.
Button mushrooms are the usual white ones at the local A&P or Piggly Wiggly or Kroger. Cremini, or baby portobello (sometimes portabella) or Italian brown are the heartier-tasting version of the white. Portobellos, you can use for hats. They have longer grower cycles... maybe cuz they're... larger? Though let me tell you, they are no substition for steak, no matter what those vegetarians tell you.
Nose about at mushroominfo.com for more of the same.
Mushrooms were the secret ingredient on iron chef america a couple weeks ago. It's true though. They throw around those white and black truffles like who cares! Thousands of dollars of who cares!