American horticulturalist, gardener, philanthropist, and art collector, who designed and planted a number of significant gardens, including the White House Rose Garden, and assembled one of the largest collections of rare horticultural books. Mellon was the second wife of philanthropist and horse breeder Paul Mellon.
She was the eldest child of Gerard Barnes Lambert, president of the Gillette Safety Razor Company and a founder of Warner–Lambert, and his wife, Rachel Parkhill Lambert (née Lowe). Her paternal grandfather, chemist Jordan Lambert, was the inventor of Listerine, which was later marketed by her father. She had two siblings. Her parents divorced in 1933, and both subsequently remarried.
Lambert married Stacy Barcroft Lloyd, Jr. in Philadelphia in 1932. Lloyd served in the Office of Strategic Services during World War II. They divorced in 1948. They had two children: Stacy Barcroft Lloyd III, and Eliza Winn Lloyd. Eliza predeceased her mother.
Lambert and her husband became close friends of the banking heir and art collector Paul Mellon and his first wife, Mary Conover, who died of an asthma attack in 1946. After Bunny divorced Lloyd, she and Paul were married, on 1 May 1948. By this marriage, she became the stepmother of Timothy Mellon and Catherine Conover Mellon (later Mrs. John Warner and now known as Catherine Conover). Together the couple collected and donated more than a thousand works of art, mostly eighteenth- and nineteenth-century European paintings, to the National Gallery of Art and established the Yale Center for British Art. The couple bred and raced thoroughbred horses, including Sea Hero, winner of the 1993 Kentucky Derby. Paul Mellon died in 1999, aged 91.
As most of her assets were invested in trusts, it was difficult to estimate Mellon’s wealth, but her family and husband’s fortune and fixed assets suggest she was exceptionally wealthy. In 2010, it was reported that Mellon had lost $5.75 million to investment adviser and convicted Ponzi scheme operator Kenneth I. Starr.
Described as a resilient centenarian, a bout with cancer and ongoing macular degeneration nonetheless slowed her activity. She was forced to give up gardening by 2011, although she continued to swim, do Pilates, and give the rare interview. On 17 March 2014, Mellon died at her Upperville, Virginia, home of natural causes, aged 103.

Link to Wikipedia biography