Here’s an interesting find:
The card says”Kristine Buttons” and “P.F. Davies Pty. Ltd., 308 Flinders Lane, Melbourne.”
P. F. Davies was a button warehouse that operated from Flinders Lane from at least 1947-1957. I have no idea who or what Kristine was!
The”plastic buttons” were made by General Plastics (the makers of Beauclaire buttons). The company changed its name from O.C. Rheuben & Co in October 1941. There are cards of the same design with the addition of “A G.P. Product” printed at the bottom. I guess that means the cards below preceed October 1941.