Can anyone identify this? It's located inside my boyfriend's great great grandfather's wood planer. Thanks!
Your boy friend is in possession of a wood plane made by the Auburn Tool Co. of Auburn, New York
This is an image of the top end of its blade.
In a semi circular arc are the words "Auburn Tool Co".
In two straight lines across the bottom are:
In the center is a depiction of a thistle flower. (The company also used a star in the center, but if forced to choose thistle or star, thistle is an easy option.)
It seems that the company was proud of their brand and on some blades stamped the words "Thistle Brand Warranted" in two lines and omitted the Auburn location.
The plane was likely manufactured in the late 19th century which is when the company was in its heyday and is when I suppose someone's great great grandfather might have been active (here I'm assuming something like thirty years per generation).
For more information you can do a web search on "Auburn Tool Co" and you can also find plenty of pictures of Auburn planes on EBay.