I just came across this lovely post card which does not appear to have been cataloged by the Library. It has a post mark of March 29, 1907, and was mailed to Miss Mollie E. Morton of Moore, Pennsylvania c/o Dr. George D. Morton - just enough information to do a search using the Library's subscription to Ancestry.com.
According to the U.S. Census, Dr. George D. Morton was a surgeon, living with his wife Josephine and their three children and two servants in Prospect Park, Pennyslyvania in 1910. One of the children is listed as Mary E. Perhaps Mollie E. and Mary E. were one in the same. If so, she would have been three years old when her aunt Mary sent the card.
How this card ended up in the Sonoma County Library's collection is unknown. Could be that in her adult life Mollie E. Morton moved to Sonoma County bringing with her memories of her childhood. Hard to say. Glad to have it regardless.