'Grain' in the Bible

Another simile he set before them, saying: 'The reign of the heavens is like to a grain of mustard, which a man having taken, did sow in his field,

And Jesus said to them, 'Through your want of faith; for verily I say to you, if ye may have faith as a grain of mustard, ye shall say to this mount, Remove hence to yonder place, and it shall remove, and nothing shall be impossible to you,