fine (white) linen

Boyd’s Bible Dictionary:

(flax). Used for stately robes (Gen. 41:4242And Pharaoh took off his ring from his hand, and put it upon Joseph's hand, and arrayed him in vestures of fine linen, and put a gold chain about his neck; (Genesis 41:42)); priestly vestments (Ex. 28:4242And thou shalt make them linen breeches to cover their nakedness; from the loins even unto the thighs they shall reach: (Exodus 28:42); Lev. 6:1010And the priest shall put on his linen garment, and his linen breeches shall he put upon his flesh, and take up the ashes which the fire hath consumed with the burnt offering on the altar, and he shall put them beside the altar. (Leviticus 6:10)); temple veil (2 Chron. 3:1414And he made the vail of blue, and purple, and crimson, and fine linen, and wrought cherubims thereon. (2 Chronicles 3:14)); choral gowns (2 Chron. 5:1212Also the Levites which were the singers, all of them of Asaph, of Heman, of Jeduthun, with their sons and their brethren, being arrayed in white linen, having cymbals and psalteries and harps, stood at the east end of the altar, and with them an hundred and twenty priests sounding with trumpets:) (2 Chronicles 5:12)), and ordinary dress. Symbol of purity (Rev. 15:66And the seven angels came out of the temple, having the seven plagues, clothed in pure and white linen, and having their breasts girded with golden girdles. (Revelation 15:6)); of luxury (Luke 16:1919There was a certain rich man, which was clothed in purple and fine linen, and fared sumptuously every day: (Luke 16:19)).

“Linen” From Concise Bible Dictionary:

Various Hebrew and Greek words are translated “linen,” and there can be no doubt that linen made of flax was known in ancient Egypt and to the Israelites; but cloths generally are called “linen” whether made of cotton or flax, some being distinguished as “fine linen,” such as was worn by the priests, kings. The word shesh, often translated “fine linen” and “fine twined linen” (for the curtains of the tabernacle, etc.) signifies “whiteness,” and is applicable to both fine linen and cotton (Ex. 26:1,311Moreover thou shalt make the tabernacle with ten curtains of fine twined linen, and blue, and purple, and scarlet: with cherubims of cunning work shalt thou make them. (Exodus 26:1)
31And thou shalt make a vail of blue, and purple, and scarlet, and fine twined linen of cunning work: with cherubims shall it be made: (Exodus 26:31)
). Joseph was arrayed in “vestures of fine linen” (Gen. 41:4242And Pharaoh took off his ring from his hand, and put it upon Joseph's hand, and arrayed him in vestures of fine linen, and put a gold chain about his neck; (Genesis 41:42)). The wrappings on the ancient Egyptian mummies were for a long time judged to be cotton, but by the use of the microscope they have been discovered to be linen.

“Wheat” From Concise Bible Dictionary:

Wheat Growing in Israel
This cereal was extensively grown in Palestine; the harvest was in May and June. In the parable it is used by the Lord as representing the children of the kingdom, the fruit of the good seed that He was sowing on the earth, in contrast to the tares, or darnel, which Satan secretly sowed among the good seed.
The Lord Himself, being the second Man “out of heaven,” is compared to the grain of wheat that must have remained alone unless it had died, but which in dying would bring forth much fruit. This clearly shows that there was no union of Christ and natural man by His incarnation alone, and that through the death of Christ the fruit produced by His resurrection is of the same order as Christ Himself (Matt. 13:25-3025But while men slept, his enemy came and sowed tares among the wheat, and went his way. 26But when the blade was sprung up, and brought forth fruit, then appeared the tares also. 27So the servants of the householder came and said unto him, Sir, didst not thou sow good seed in thy field? from whence then hath it tares? 28He said unto them, An enemy hath done this. The servants said unto him, Wilt thou then that we go and gather them up? 29But he said, Nay; lest while ye gather up the tares, ye root up also the wheat with them. 30Let both grow together until the harvest: and in the time of harvest I will say to the reapers, Gather ye together first the tares, and bind them in bundles to burn them: but gather the wheat into my barn. (Matthew 13:25‑30); John 12:2424Verily, verily, I say unto you, Except a corn of wheat fall into the ground and die, it abideth alone: but if it die, it bringeth forth much fruit. (John 12:24); 1 Cor. 15:48-4948As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly. 49And as we have borne the image of the earthy, we shall also bear the image of the heavenly. (1 Corinthians 15:48‑49)).
There are three or four varieties of Triticum grown in Palestine.

Strong’s Dictionary of Hebrew Words:

from an unused root (of the same form) meaning to bleach, i.e. (intransitive) be white; probably cotton (of some sort)
KJV Usage:
fine (white) linen