Plenty of schools go on pumpkin patch field trips. Some get to visit grizzly bears at Northwest Trek. But there’s only one school where you get to grow pumpkins, then hide them for grizzly cubs to find – and that’s Weyerhaeuser Elementary, whose second- and third-graders came to Northwest Trek early this October (and last year too) to do exactly that. It’s all part of the school’s focus on outdoor STEM education, helped along by volunteer expertise from Trek horticulturalist Jake Pool. “Look, this one’s enormous!” cried one boy, stepping between vines to a giant Cinderella pumpkin. “And this one’s …