The garden center was abuzz with hay rides, food trucks and kids games on a sunny Saturday. But the stars of the show at a Mount Vernon nursery in late September were 14 mind-bogglingly large pumpkins, drooping over the wooden pallets they rested on. Pumpkin growers, families and community members descended on Christianson’s Nursery for the Skagit Valley Giant Pumpkin Festival. Parents told their kids “those are real pumpkins!” and took photos as toddlers hugged fruits that dwarfed them. Growers came from Lynden to Oregon City, Whidbey Island to Omak, for their shot at glory and a $2,000 grand…