Kennett Square Pennsylvania is knows as the mushroom capital of the world, and for good reason, this area has been a hub of commercial mushroom cultivation for many decades.  The scenic town just West of Philly hosts an annual street fair, this year will be the 38th, to celebrate it favorite agricultural crop, and if you've never been, I'd recommend it.  It really fun(gi)!  

For your convenience, here's a link to the website for additional deets, and here is a fun(gi) video to tell you more.