The source of that mini-ball of butter that The Davenport Hotel puts on dinner plates is a Grand Rapids, Mich., factory with a familiar name: Butterball Farms Inc. And yes, through their common founder, Butterball is related to that other, better-known raiser of your Thanksgiving centerpiece. Butterball is also a founding member of The Source, an experimental collaboration among 16 Grand Rapids businesses and Michigan social service agencies. Butterball Chief Executive Officer Mark Peters and Andrew Brower, executive director of The Source, were in Spokane last week to explain the program to Washington work force training and economic development officials.