Got this coin, which bears all the marks of a British 1902 3d coin but it's nowhere near as big. A normal 3d is about 16mm across, this is only around 12.5mm: 3d wasn't circulated in Australia until 1910 AFAIK. Can anyone identify it?
Yes - almost certainly comes under the heading of "toy money". Produced from around the 1840s to the early 20th century in loose imitation of coins of the realm, or sometimes fantasy designs. Much by Lauer, and the tradition possibly originating in Germany. It is collected, but I know little more than this. Yours, being in fairly corroded state, is probably of no great value.