I recently found a myrtlewood tie tack at my favorite thrift store and wondered how many jewelry items are made with myrtlewood. So on to google and searching for myrtlewood jewelry. I found relatively few references to myrtlewood jewelry, mostly from shops along the Southern Oregon coast. Of those I found only one offering tie tacks.
However, I found a good bit of information about the myrtlewood tree, which grows only in Southern Oregon and Northern California. This slow-growing, broadleaf evergreen produces a dense, richly grained wood with sculpted patterns akin to lace, flames and tiger stripes. Its colors, influenced by minerals in the soil, are unmatched in elegance, yielding hues of blond, honey, soft gray, and every shade of brown. One website has a page of photos of the various colors found in myrtlewood.
Most of the shops I found on google are described in an article by Laurel Gerkman in Oregon Coast Magazine (2007). This cottage industry dates back to the late 1800s.