Verses with the word plate in the Old Testament (3 verses):

Exodus 28:36
And thou shalt make a plate of pure gold, and grave upon it, like the engravings of a signet, HOLINESS TO THE LORD.

Exodus 39:30
And they made the plate of the holy crown of pure gold, and wrote upon it a writing, like to the engravings of a signet, HOLINESS TO THE LORD.

Leviticus 8:9
And he put the mitre upon his head; also upon the mitre, even upon his forefront, did he put the golden plate, the holy crown; as the LORD commanded Moses.