Ethel de Forest (1887-1962) was the daughter of an American Congressman, Robert Weekes de Forest. The family were of Huguenot ancestry, descendents of Jessé de Forest who fled persection in Wallonia to the New World in the early 17th century. He was born in France. Ethel married Allen Earle Whitman (1872-1915) who died when he was 40, then married Henry Rowland Vermilye. She had two children with each husband.
The castle in the panel is unidentified. The coronet at the top may be for a French comte. The fleur-de-lys is associated with France. They could just be decorations.
Bookplate (click to enlarge)