Well I have a bunch of unpublished Beyazid I and Beyazid II Mangirs. Some
types look like yours.
However, your coin is an anonymous Mangir. Most likely from the
area of Galipoli. Hence, it may be a local issue by the Saruhan Beylik. But no one can be certain.
Nuri Pere assigned this coin wrongly to Osman Gazi. There are only 2 specimen known of a coin that reads Osman bin Ertugrul.
Your coin is a Beylik issue. It may even be Karaman.
These coins are common and often mistaken as Osman Gazi because of
Nuri Pere. But Cuneyt Olcer cleared this up.
If you would like to sell this coin to me please let me know. I would be very interested.
Best wishes,
burak