A lot of “polka” goods arrived from the European polka craze from the 1840’s, including the polka hat and polka jacket, but just the polka dot (along with the dance by itself) appears to have caught all over. Most likely we take the pattern from granted now, but polka dots https://polka-dot-official43197.tribunablog.com/the-definitive-guide-to-polkadot-official-store-43583632