In 2009, Berkeley seniors Nikhil Arora and Alejandro Velez started to geek out over something they'd heard in a lecture: you can grow a healthy crop of mushrooms on used coffee grounds. Intrigued by the business potential, the pair set aside jobs in finance and consulting and became urban farmers: salvaging leaky bags of coffee grounds, planting mushroom spawn in an Oakland warehouse, and selling their crop to local grocers. Over time, the partners realized they could help others grow food for themselves, so they stopped farming fungus and took the leap into selling tabletop grow kits, seeds, and potting soil. Since launch, Back to the Roots has become the fastest-growing organic gardening brand in the U.S., with its products sold in 10,000 stores across the country.