E Pluribus Unum

Walking back down Parnell Street in Strathfield to my car the other evening, I saw a coin glinting on the pavement and picked it up. Not so very far along the same street, I picked up another. The light wasn't good enough for me to see what they were, and even when I came home I had to look at them through a magnifying glass. The first is a small golden 1977 Hong Kong twenty cent piece, with crenallated edges and Queen Bess II on the back. Lot of Chinese live in Strathfield so I guess that explains that. The other turned out to be a 1907 US nickel, with a big Roman V, flanked by wreaths, on one side and Liberty, her face almost effaced, on the reverse. How on earth did that get there, I wonder?