Hi! Freelance fashion historian here! Pilgrims never actually wore “buckles” on their hats. The image we stereotypically associate with them is actually based on English Puritan fashions of the Stuart Era. The image we have of them now was made popular in the artwork of the late 19th century. During the actual 17th century many hats do indeed resemble those seen on our contemporary images of pilgrims, but these buckles are noticeably absent. There were occasionally square ornaments or broaches on the band of the hat, but never buckles.