Definition of pilgrim's badge in US English:

pilgrim's badge

(also pilgrim badge)

noun

historical
  • A token, usually a small metal badge imprinted with a particular emblem or in the shape of a scallop or cockleshell, worn, especially by medieval Christians, to indicate the completion or undertaking of a (particular) pilgrimage.

Origin

Mid 17th century; earliest use found in Thomas Fuller (1607/8–1661), Church of England clergyman.