I accept that Jesus spoke in parables and yet gave his true followers understanding of them.These scriptures that you are referring to is one of Jesus illustrations that focuses on the gathering of those who will rule with Jesus in his Kingdom. I accept the following explanation....Who is the man who sowed the fine seed in his field? Jesus provides the answer when he explains to his disciples: The sower of the fine seed is the Son of man. (Matt. 13:37) Jesus, the Son of man, prepared the field for planting during the three and a half years of his earthly ministry. Then from Pentecost 33 C.E. onward, he started to sow the fine seed...the sons of the kingdom. This sowing evidently took place when Jesus, as God's representative, began to pour out holy spirit upon the disciples, thereby anointing them as Gods sons. The fine seed developed into mature wheat. So the objective in sowing the fine seed was eventually to gather the full number of those who would become joint heirs and rulers with Jesus in his Kingdom.
Luke 22:28-30
28 However, you are the ones who have stuck with me in my trials; 29 and I make a covenant with you, just as my Father has made a covenant with me, for a kingdom, 30 so that you may eat and drink at my table in my Kingdom, and sit on thrones to judge the 12 tribes of Israel."
Revelation 20:6
6 Happy and holy is anyone having part in the first resurrection; over these the second death has no authority, but they will be priests of God and of the Christ, and they will rule as kings with him for the 1,000 years.
Then, who is the enemy, and who are the weeds? Jesus tells us that the enemy is the Devil. The weeds are described as the sons of the wicked one.
Matthew 13:37-39
37 In response he said: The sower of the fine seed is the Son of man; 38 the field is the world. As for the fine seed, these are the sons of the Kingdom, but the weeds are the sons of the wicked one, 39 and the enemy who sowed them is the Devil. The harvest is a conclusion of a system of things, and the reapers are angels.
You see....Jesus himself gives the meaning of the parable.
In his parables Jesus always used simple everyday things that his listeners were familiar with. The weeds that Jesus referred to were probably the bearded darnel. This poisonous plant closely resembles wheat in its early stages before it reaches maturity. In time a great apostasy developed. These hypocritical Christians who claim to be followers of Christ are really part of the seed of Satan the Devil.
Perhaps this sounds harsh but I believe as Jesus tells us...during the last days of this wicked system of things, a separating takes place...the sons of the Kingdom are to be gathered and separated from any weedlike ones.