From the Atlantic to the Pacific, a warm, wet winter promises bumper crops of pollen. Thanks to an extremely mild winter, trees across much of the U.S. - including maple, alder, cotton wood and oak - are budding two to three weeks early, filling the air with their irritating pollen. Add torrential rains, and you have the makings of what some experts predict will be the worst allergy seasaon in 20 years.