Finders Keepers … and then shut up.
> so I took it home and washed it clean <
I hope he did nothing more than run a little water over it. Many rare coins have lost value by cleaning them too vigorously.
Always consult with an expert first.
Ocho Reales were legal tender in the US until 1857. They were often cut to “bits” to fractionalize the value. There was 8 (Ocho) bits to a coin and that’s where the term “two bits” meaning a Quarter Dollar came from.