The problem with items like this is that there seems to be no veryfiable context, such as archeological field reports, that can be brought in. As a former curator, I can assure you that the tales that come with an offered artefact are just that, tales, until they can be proven right, or not. From what you have given as information, there is no assurance of what period or where these items came from.
So far, it can be shown they are not British, American, French or Spanish naval buttons of a known pattern. Perhaps an unofficial or merchant marine lot of sailor's buttons then? There is no universal source on naval buttons that I am aware of. In any, event, without a strong and proven context, as explainbed above, these buttons must remain interesting curiosities upon which no viable conclusion can presently be drawn.
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