Mustard is likened unto both faith, and the Kingdom of Heaven.
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.
21 Howbeit this kind goeth not out but by prayer and fasting.
II Kingdom of Heaven
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:
32 Which indeed is the least of all seeds: but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof.
The point of both of these is that from the smallest things may well come forth the greatest of things.
33 Wherefore, be not weary in well–doing, for ye are laying the foundation of a great work. And out of small things proceedeth that which is great.
We Are Sowing (216)
Verse 3 Seeds that lie unchanged, unquickened, Lifeless on the teeming mold; Seeds that live and grow and flourish When the sower's hand is cold. By a whisper sow we blessings; By a breath we scatter strife. In our words and thoughts and actions Lie the seeds of death and life. Verse 4 Thou who knowest all our weakness, Leave us not to sow alone! Bid thine angels guard the furrows Where the precious grain is sown, Till the fields are crown'd with glory, Filled with mellow, ripened ears, Filled with fruit of life eternal From the seed we sowed in tears.