I’ve painstakingly nurtured windowsill basil plants, and shooed ambitious animals out of past gardens. I might not have a bright green thumb, but there’s at least a hint of pale green there. But grow mushrooms? Don’t mushrooms just appear from little forest elves, or some such magical place?

It turns out they can appear from used coffee grinds, too—and this smart, sustainable product (it uses old coffee from Peet’s!) lets you grow mushrooms in a box, right on your windowsill.

I just opened the package and set it behind our Reader’s Digest art team, where it’ll get a nice bit of sunlight. I gave it a good spritz of water… now we just have to wait and see what grows. Mushrooms are supposed to sprout in 11 days, so I’ll bring you a report after Labor Day.

Want to grow your own? Back to the Roots Kits are sold at Home Depot, Safeway, Whole Foods, and Bed Bath and Beyond.