Yoma, Chapter Three, Mishnah Nine
The high priest now proceeds to the two goats, one which will eventually be sacrificed and one which will be sent to Azazel.
1) He then went to the east of the Temple court, to the north of the altar, the deputy high priest at his right and the head of the [priestly] family [ministering that week] at his left.
2) There were two goats and an urn was there, and in it were two lots.
3) They were of box-wood and Ben Gamala made them of gold and they would mention his name in praise.
Section one: The high priest now turns to the east of the courtyard, to the northern side of the outer altar. With him are the deputy high priest and the head of the priestly family whose turn it is to serve in the Temple. The priests were divided up into 24 priestly families, and each served a week in the Temple. Each division was divided into families, and each family would take one day of the week. The mishnah refers to the head of the family whose luck it was to have Yom Kippur fall on their day.
Section two: Waiting for the high priest were two goats, as mentioned in Leviticus 16:5 and onwards. They will figure prominently in the days service and are perhaps its most famous element. Next to the two goats was an urn with two lots in it, as mentioned in 16:8. The lots will be used to determine which goat is sacrificed and which goat goes to Azazel.
Section three: The lots were originally made of box-wood until Ben Gamala, who was a high priest, made them of gold.