Hi. Nice collection. In the 1870's to the 1920's clamming in the US for shell to be made into buttons resulted in Zillions of pearls of all
shapes being found. The junk went to China to make some kind of herbal calcium med. The off round to smooth baroque usually went
to India and lastly the best ones went to Paris and London where they were sold to know jewelers or collectors. Actual traces of specific pearls are very hard to come by. There are a few books and articles about the button industry combined with pearling. My state wisconsin was noted for exceptional quality pearls. Rem: there were only 1 round one in a million mussels. Mississippi River yielded thousands of tons of material and button factories existed from Minneapolis to St Louis and even on some large tributary Rivers such as the Upper Iowa, Rock
Des Moines among others.