I'm super new to this but I found this in my backyard and have no idea what it could be? It's metal, but I'm not sure which kind.
Oh yes! It seems to me probably a copper fallus (there are too much crusts e deposits on the flan), type Mamluk Baibars, from Damascus (Mamluk Sultanate of Egypt and Syria).
Thanks for the info! Is there a way I can gently clean some of the sediment away? Is warm water okay?
Yes! I usually dip the coins into kerosene or olive oil and forget them for a few weeks. After that time, I clean them with a hard-bristled toothbrush.