police officers received an uncorroborated and anonymous tip that a farmer was growing marijuana on his property. the police went out to the farm, and finding no one home, went around the back, and followed a path that led out to the adjacent fields where cattle and horses were grazing. at the farthest edge of the property there were about two dozen marijuana plants. the plants were obscured by a high hedge fence, but the officers walked through the hedges and found the plants.