Green grass and snow-capped mountains are the signs of spring in Jackson Hole. Jackson Hole real estate activity: Interest rates are down this morning, according to T.R. Pierce at Bank of Jackson Hole, with the 30-year fixed rate mortgage at 4 percent. NEW: 4-bed, 4,720-square-foot home in Wilderness Ranches near the banks of the Snake River, $3.86 million. NEW: 40-acre building site on Porcupine...