Came home with a cute little $1 carpenter's square yesterday. Small 8 X 12" steel baby. I was attracted to the logo, of course. Cleaned it up a bit with light oil and fine steel wool.
Found this: 23mm. circle containing: The Riverside Tool Co New York. Inside is a 20mm. circle containing: Celebrated Blue Seal Trade Mark. Inside that is a nice anvil. Inside the anvil is R. T. Co. (the o fits inside the C.)
Haven't found much on the company--but enough to know that it is not the same as Lakeside Tool, the Montgomery Ward line.
Go to it, guys!