TerraClear’s bid to upend the farming industry by using advanced technology to help farmers clear rocks from fields is producing a reliable crop — cash. The startup just closed a $6.1 million funding round led by Madrona Venture Group  to bring its total capital raised to more than $13 million since launching in December 2017. Based in Bellevue, Wash, and in the farming community of Grangeville, Idaho, TerraClear was founded by Brent Frei, the former CEO of Onyx Software who co-founded Smartsheet in 2005.