PCA pastor and visiting professor at Covenant Seminary Tim LeCroy has a great article dealing with the presbyterian origins of the clerical collar.

Here we see several members of the 18^th c. Church of Scotland (Presbyterian) having their hackles raised over some ostentatious clergymen wearing scarlet cloaks and cravats. Later they hold a Synod where they decide that they ought to wear black gowns and to make use of neck bands. This paragraph shows us two things: the wearing of cravats was considered to be distinctive clerical garb, and the synod of the kirk decided ultimately that modest use of neckbands was permitted…