Among Mary's achievements in Ogallala, Nebraska, starting in high school, she was a rodeo queen, national merit semi-finalist, valedictorian of her high school class, and Episcopal Church organist. Among her awards at the University of Nebraska were graduating with highest honors and being selected as both the Nebraska State Student Nurse of the Year (1971) and an Outstanding Young Woman of America.

Mary went on to receive a Masters of Public Health in Maternal Child Health from Tulane University School of Public Health, and her Doctor of Medicine degree from the LSU School of Medicine, New Orleans, Louisiana. She was board-certified as a pediatrician by the American Board of Pediatrics after completing a residency at the University of Texas Medical Branch, Galveston, Texas and subsequently passing the Boards. Mary and her family relocated to Berkeley, California in 1982 where she was a community pediatrician and partner with East Bay Pediatrics until her retirement in 2014. Throughout this time she maintained privileges and saw patients at Children’s Hospital Oakland. She was the director of Katie’s Clinic for Rett Syndrome and Related Disorders (Children’s Hospital Oakland) beginning in 2008 and a pediatrician and founding member of the clinic since its inception in 2004. Mary was passionate about research in the field of Rett Syndrome and related disorders, participating in clinical trials, collaborating on several publications, and presenting on the benefits of an enriched environment.

Mary's parents were Ercel and Nina DeLay. Her sibling is Michael DeLay, and his wife, Mary DeLay of Grand Island, Nebraska. Mary married William Clay Jones, III on May 25th, 1975 in Ogallala, Nebraska.

She is survived by her spouse, William Clay Jones, III of Berkeley, California and her children, Trevor Clay Jones (Anna), Jennifer Mary Jones Lokotkin (Yuriy), and Seth Michael Jones (Kelsey). She was very proud of her three grandchildren, Lauren (age 8), Matthew (age 5), and Dalia (age 2). Mary was grateful her children and grandchildren continued to reside in Northern California for frequent visits.

Mary loved A’s baseball, going to Yosemite, beach vacations with her family, photography, and cooking. Over the last two years, Mary was given the privilege of taking care of her granddaughter Dalia two days per week. This was a joyous time in which Mary and Dalia visited parks and the horse barn, did art projects, read books, made blueberry muffins, identified seashells gathered from the Atlantic Ocean to Guam, and checked on the local wildlife in Berkeley including deer in the garden and beautiful Monarch caterpillars. In recent years, Mary also regularly drove to Fremont to see grandchildren Lauren and Matthew and help with school drop-off and pick-up, many times going on outings to the pumpkin patch or the animal farm. More recently Mary put together a creative Halloween celebration in her driveway for Lauren and Matthew, even driving across town to find dry ice for making spooky Jack-O-Lanterns. Despite the pandemic, Mary found ways to make her grandchildren feel loved and special.