As the growing season progresses some of the longer season crops start to mature. This is Glass Gem Corn, an older heirloom popcorn developed by Greg Schoen and Bill McDorman. It's a cool story about breeding and developing old corn varieties of the Native Americans, here's a link.
With a date to maturity of 110 days, it will take up most of the summer but it's well worth the effort. I haven't yet tried to pop the corn, so we'll see. The kernels can also be ground into cornmeal which sounds even more interesting than popcorn!!