"The YELM Earthworm & Castings Farm is one of the largest worm farms in North America. We are dedicated to soil conservation, restoration and improvement. The farm began operating in the mid-1980s as a mushroom farm. It was redeveloped as a worm farm in 1990 and was revitalized in 1997 through new management. We have excellent facilities, including more than 30,000 sq. ft. of enclosed production space and well water. The farm is full of charm, including our farm office housed in an old-time rail caboose.
We use time-tested, proven methods to grow large quanities of redworms (Eisenia fetida). The redworms are grown with solids-separated dairy manure and gathered using a two-step mechanical/hand sorting harvesting process. We are a full-time, full-service commercial redworm farm. We provide redworms for all types and sizes of projects for gardeners, home composters, farmers, institutions, and entreprenuers.
Visiting the Yelm Earthworm and Castings Farm...

Hours: (subject to change)
The Yelm Earthworm & Castings Farm and the Soil Building Depot is open to the public Monday through Saturday from 10 am to 6 pm.," quoting their site.