That is a big pearl. I would not expect edible oysters to grow such a big pearl. Were the oysters edible? Or did you find them in the ocean yourself?
Although all oysters are capable of bearing a pearl, some are more valuable than others mainly because of the luster which is the most important pearl characteristic.
It is hard to see from the photo if your pearl is lustrous or not. If so, your pearl would have some value mainly because of its size and nice round shape. It certainly looks like a "keeper", but then to me all pearls are "keepers".
Thank you for sharing and I loved seeing the photo!