SammO and SammoS were brand names of the Samuel C. Osborn Manufacturing Company of Chicago, Illinois. Samuel Osborn opened a music tuition and instrument distribution company around 1900. By 1906 he had shops in Oakland, San Francisco and Los Angeles as well as music teaching conservatories around the country. His music schools needed a lot of instruments and in 1916 he started his own manufacturing company in Chicago. The company made acoustic guitars, mandolins and banjo-ukes often using koa. In 1919 he opened an ambitious new factory using production line techiques to make pianos - this led to cash flow problems for Osborn who was forced to restructure his company. In 1922 Osborn died of complications following an appendectomy operation, aged just 47, and his company finally ceased trading.
Source: Samuel Osborn catalog 1920