Adam Clarke on Exodus 39:30

The holy crown of pure gold - On Asiatic monuments, particularly those that appear in the ruins of Persepolis and on many Egyptian monuments, the priests are represented as wearing crowns or tiaras, and sometimes their heads are crowned with laurel. Cuper observes, that the priests and priestesses, among the ancient Greeks, were styled στεφανοφοροι, or crown-bearers, because they officiated having sometimes crowns of gold, at others, crowns of laurel, upon their heads.