This is a S. Kirk & Son, Inc. (Stieff) Repousse sterling silver Serving Spoon marked "Sterling". The mark indicates a date between 1924 and 1932.  The antique spoon measures about 8.5 inches.   The spoon were inherited over 40 years ago from an elderly couple that had inherited them themselves and is monogrammed on the back with the name of the original owner, "Elizabeth". As I knew the owner, the date range of 1924 to 1932 fits.  The spoon is in wonderful condition having been kept in a silver chest and only shows light wear despite its age.  (See photos) 

Repousse silver by S. Kirk & Son, Co. (aka Kirk Stieff), the oldest silverware pattern produced in the United States, debuted in 1828 as Hollow ware and as Flatware in 1846. The pattern is ornately elegant with an intricate floral design.

This piece of Sterling Silver Repousse is marked S. Kirk & Son, Inc. Sterling on the back. Please note that the Silver maker's mark for the Repousse pattern evolved over time. Some pieces are marked S. Kirk & Son, S. Kirk & Sons; S Kirk & Son Co; S. Kirk & Son, Inc., Kirk Co; Stieff; Kirk Stieff, etc.

For more information:

http://www.thestieffcompany.com/The_Stieff_Company/The_Story_of_the_House_of_Kirk.html