Farmers with a valley at LV 5 or higher can create a sponsor code at the Homestead. New farmers enter the code, or open your link, to become your kindred.
Whenever your kindred spend YIELD on packs, upgrades, wisps or market purchases, you instantly receive 1% back. It comes out of the amount that would have been burned, so it never costs the buyer extra. A farmer can only have one sponsor, and it can't be changed.