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As a family-owned company, they really value the loyalty of their customers and employees. With over eighty years of experience behind them, the Magrath family is looking forward to serving their customers and the community for years to come.


Diamond K Supply Co. opened its doors in Lafayette for the first time in 1936 at 3671 Mt. Diablo Blvd. and is one of the oldest continuously operating companies in Lafayette. In those days, Lafayette was much smaller and more rural. Mt. Diablo Blvd was Highway 24, and there was just one lane in either direction. To meet the rural needs of the town, Ogden Kiesel, a resident of Lafayette, opened Diamond K Supply Co. as a feed and fuel store selling hay, feed, firewood and coal. To call the shop, Ogden Kiesel used the livestock brand in his call and put the "K" of his last name in a diamond resulting in the birth of the Diamond K Supply Co. brand.


In 1947, World War II veteran Bill Magrath and his partner, Nancy, bought an interest in Diamond K, where Bill Magrath spent the next 43 years managing and developing the company he loved. Soon, Bill and Nancy Magrath assumed full ownership of the company, and since 1948 the Magrath family has proudly owned and operated Diamond K Supply. In addition to Bill and Nancy, all the members of the Magrath family worked for Diamond K at one time, including the daughter of Anne Magrath Coleman and the sons of Bill Magrath and Miler Magrath. Even though our founders, Bill and Nancy Magrath, have passed away, the Magrath family still owns and operates this company. Miler Magrath was president of the company from 1990 until his passing in 2017. Bill Magrath is the company's acting President and General Counsel. Anne Magrath-Coleman is the acting Vice-President of the Commission.


Over the years, Diamond K has extended its facilities, increased its distribution capacity and increased its goods to meet the needs of its customers. On their website, they hope to introduce you to a variety of their products and their ability to meet the needs of each of their customers. The Magrath family and all their staff are eager to help you. Only go to their store or give them a call.


One of the things they pride themselves on is the simple , easy delivery of their landscaping supplies. Depending on the project, they are also able to offer service to many of their goods the next day. For all of their shipping rates, please call and they'd love to help.

If you are looking for the best landscaping supply stores near Walnut Creek, California, you’ve got to check out these amazing stores: 


  • Mt Diablo Landscape Center

  • Diablo Mulch & FireWood

  • Downtown Walnut Creek Ace Hardware

  • MacAlvey's Nursery & Landscape Material

  • Ecomulch

  • SiteOne Landscape Supply

  • Sloat Garden Center

  • Morgan's Masonry Supply


After visiting these lovely supply stores make sure to stop by and say “Hello” to us at 1261 Locust Street in Walnut Creek, California!

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