In Vault City, behind Cassidy's bar and Dr. Andrew's Clinic with the half working Auto-Doc, there is a stagnant family with neither the resources to leave town, nor to earn their sustenance.
Speaking to Mr. Smith will reveal a possible way to help them earn a living; Happy Harry has a plow for sale, which would make farming much easier. Happy won't let the plow go for the goodness of his heart, though. 800 caps, up front. A Barter check (51% required) will reduce the cost to 600. Buy it when you've got the funds.