antique coin from medival age

This is a coin from earlier times than Muhammad Bin Tughlaq. the inscription is in ancient arabic. there is a story behind the finding of the coin. it was in the collection of my great grand father. however he was not a collector.

the coin is made of brass metal which were common in that era. after doing my research i found that it is unique and genuine as all the details of not being a counterfeit was accomplished by it.

such as:

1. the coin print is not exactly in center. and varies in all the coins i have.

2. the inscription on the edge are flat.

3. the insertion point from which the metal was poured in the casting is elevated and not exactly in the same area of all the coins.

4. the uncleaned coins shows a rainbow discoloration which can only be found on old metals

5. its in perfect condition. with signs of usage.

I have a few more with me. pls ask me if you need those but pls consider that i'm gonna keep at least one as a souvenir.

i do not know the right value of the item so pls help me determine the value of it.

Thanks