Don't know if it is WWI or WWII or British or Australian. Don't know if it is a button or part of a tie pin or a lapel badge.
It is a bit smaller than a 5c coin which is about 1cm dia.
Only found the one. It may be upside down ? in the image.
United States forces in Australia
The first Americans arrived in Brisbane on 22 December 1941, and by mid 1943 the number in Australia had risen to 150,000 with the largest concentrations in Queensland near Brisbane, Rockhampton, and Townsville. US naval forces were also frequently anchored at Sydney and Perth, and General Douglas MacArthur, who became the Supreme Commander of South-West Pacific Area on 18 April 1942, initially established his headquarters in Melbourne. The social impact of the Americans was considerable with Australians influenced by American trends in fashion, manufactured goods, domestic technology, and consumerism. Cafés began advertising Coca-Cola, coffee, and hamburgers, hot-dog stands appeared, and American cinema influenced Australian fashion. By the end of 1944, two-thirds of Australia’s imports came from the United States.
Among my late father's possessions. No sign of any others of a set. Yes US forces were stationed in Qld. before the battle of the Coral Sea.
My father served in Australian Army in Middle East and in Pacific.
I now have a reply. It is not Australian or British and probably not American.
It may not be part of a military uniform but something related to a military service organisation.
In Australia we have Legion Clubs and RSL Clubs and Legacy.