This is a variant spelling of the Old French pre-medieval "Soumon" or the English "Salmon", both of whom translate as "the son of Solomon", although there is some minority view that the name may have been a nickname for Salmon (the fish). Perhaps oddly, to 20th Century eyes, fish were highly regarded as heraldic symbols, particulaly in France. The Dauphin of France having a dolphin as his personal charge. The name as Solomon was particularly popular with the Crusaders and was an early introduction into England. The spelling with the intrusive "s" would appear to be a very late dialectual variant. The first recorded spelling of the family name is shown to be that of William Saumon. which was dated 1273, in the Hundred Rolls of Lincoln. during the reign of King Edward 1, known as the Hammer of the Scots, 1272 - 1307. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.