Monograms
In the mid 1930s monogram buttons were in vogue.

The Mercury (Hobart), 13th April 1933 page 10.
Commenting on cool fashions for hot Queensland summer days …

Townsville Daily Bulletin (Qld), 2nd November 1935 page 8.
Men also were in on this trend …

The Mail (Adelaide), 30th March 1935 page 7.
They were also fashionable in 1947-8. From a David Jones advert in 1948:

The Daily Telegraph (Sydney), 15th April 1948 page 11.