Indeed it is Mushroom Popcorn and the only place I've found that sells it in home use consumer sized packages is www.justpoppin.com
I make a lot of homemade caramel popcorn and mushroom popcorn is the only way to go because the regular popcorn breaks into bits when trying to get it all coated completely.
I've gotten samples of different mushroom popcorn varieties from local kettle corn makers at the craft fairs and such and I even once bought a 50 LB bag from a pretty famous concession supply company but it doesn't come close to the mushroom popcorn at justpoppin.com
I don't know what it is but almost all of their popcorn pops into the ball shapes where the other stuff I have tried, including the 50LB bag only popped about 1/2 mushroom.
Besides, they're located not too far from me so I can get it delivered really fast.
Anyway, that's my 2 cents. I'm off to the kitchen, I just made myself hungry. — June 16, 2009 3:29 p.m.