Seattle Tilth
Seattle Tilth has some serious volunteer programs. Right now they are looking for people for their Soil and Water Stewardship program. This is nine-months of training in sustainable food production and natural resource conservation. You can apply what you learn in your own community through hands-on projects like building garden beds, installing rain gardens and creating habitat for wildlife and pollinators. You can also help out at special farms or gardens around the city.
Visit their website if this sounds interesting to you!