Yakima, WA 98902 (509) 248-3263 Fax: (509) 225-2702. Monday to Friday, 8 a.m. to 5 p.m. Contact Us. Our Providers. Our Services. For Patients. Patient Portal. About Memorial Cornerstone Medicine. From its origin more than 30 years ago as a three physician practice, Cornerstone Medicine has grown into one of the largest primary care clinics in ....