Several months ago I bought a handful of scruffy Islamic coins to ID for fun. Ive managed some, which are now labelled and added to vast coopertron archives. However, these four are giving me trouble and after sat on a tray in the lounge all this time, they're making Mrs Coopertron rather grumpy.
On Numista, you could use search fields "polygonal" and "copper" and bound the time to before 1900, and see what comes up in India (I tried, and there is quite a bit, although many of them are square, but also some oblong ones like yours). maybe you've already looked over there .