The first known use of wreaths was in the ancient Etruscan civilization of Italy, but they were popularized by the ancient Greeks.
They used them as status symbols. The god Apollo was always depicted wearing a laurel wreath and winners of the Olympic games received olive wreaths as prizes.
Farmers would also make wreaths from their crops and hang them on their doors to celebrate and thank the gods for a bountiful harvest.
Eventually, Christians began to use holly wreaths at Christmastime, and German Lutherans in the 16th century started hanging four candles in them to light for each of the four weeks of Advent.