Gold is an expression of kingship on Earth, Gold was a highly valued metal and worn by rulers in crowns or other jewellery. Christians believe that Christ is the true king who now reigns in heaven. Jesus was also descended from the line of David, the greatest King of Israel who the Jews of Jesus' day yearned to see return and free them from oppression at the hands of the Romans (although Jesus is ultimately not this kind of Messiah)
Finally the myrrh is an embalming ointment that was used for anointing the dead. This therefore is representative of Jesus’ future suffering and death. Jesus' resurrection was indeed discovered by women coming to anoint his body - however there is no mention that this myrrh is what they intended to use.
When He is King we will give Him a King's gifts,
Myrrh for its sweetness, and gold for a crown,
Beautiful robes", said the young girl to Joseph,
Fair with her first-born on Bethlehem Down.
Bethlehem Down is full of the starlight,
Winds for the spices, and stars for the gold,
Mary for sleep, and for lullaby music,
Songs of a shepherd by Bethlehem fold.
When He is King they will clothe Him in grave-sheets,
Myrrh for embalming, and wood for a crown,
He that lies now in the white arms of Mary,
Sleeping so lightly on Bethlehem Down
Here He has peace and a short while for dreaming,
Close-huddled oxen to keep him from cold,
Mary for love, and for lullaby music,
Songs of a shepherd by Bethlehem Down.