smallish cast iron ashtray

Not sure of much of anything about this one except what y'all see here. It *did* get a little bit of wire-brush treatment to lose the worst of the rust on its topside -- seemingly it has spent a good deal of time in its past "outside" someplace where it regularly got filled with rainwater/etc instead of just cig butts. Its underside seems to show remains of a black finish, (like a typical cast iron skillet) there are no markings whatsoever on it anywhere.

Its shape kinda reminds me of a "spade" (as in playing cards) which makes me wonder if it might to used to have had 3 others with it in the general shapes of club/diamond/heart -- but that is complete conjecture on my part.

Clues WELCOMED if anybody recognizes anything about it! :-) :-) :-)