Verses with the word grain in the New Testament (6 verses):

Matthew 13:31
Another parable put he forth unto them, saying, The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field:

Matthew 17:20
And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.

Mark 4:31
It is like a grain of mustard seed, which, when it is sown in the earth, is less than all the seeds that be in the earth:

Luke 13:19
It is like a grain of mustard seed, which a man took, and cast into his garden; and it grew, and waxed a great tree; and the fowls of the air lodged in the branches of it.

Luke 17:6
And the Lord said, If ye had faith as a grain of mustard seed, ye might say unto this sycamine tree, Be thou plucked up by the root, and be thou planted in the sea; and it should obey you.

1 Corinthians 15:37
And that which thou sowest, thou sowest not that body that shall be, but bare grain, it may chance of wheat, or of some other grain: