Crowns of flowers were worn during religious festivals and to welcome important guests. It was a custom to present a golden wreath to important visiting officials at their parousia, i.e. their coming.
Even today, crowns made of yellow Spurge (Euphorbia), are worn during spring festivals in parts of Asia Minor. In antiquity, this flower was identified as having magical powers of immortality. Eventually, these flowers would fade and die, but the crown promised to those who overcome (Revelation 2.10), is a crown of life that never fades away and therefore is a type of eternal life.