Similar stems are known to have been made by Cambridge and Bryce, but the base of this stem does not quite match either of those companies. The design is pressed and not cut and so far our best guess has been that these are probably L. E. Smith.
"The guess that this might be L. E. Smith was a very good one. It was made by Smith in blue circa 1935. It was also made in crystal for a considerably longer period of time, from circa 1933-1944. The Wible family (descendants of the co-founders of the company) have a milk glass pilsner in their private collection that has been crimped, converting it into a bud vase." --Tom Felt
