Matthew 13:37-43: The Parable of the Good and Bad Sowers.
Since I have already covered these verses in this article, I will not cover them again here. However, I do want to point out that the three previous parables on the mustard seed (here and here) and leaven and dough stand in between that original telling of this parable and its explanation by Christ to the apostles. I believe that this is because all three parables so far and the three following ones are part of a complete picture.
Christ is careful in maintaining the constency of his metaphor about "seeds" only coming from the spirit. Notice that he describes hatred (the evil one in translation) as sowing weeds, not seeds. His story of the mustard seed makes the connetion between seeds and the kingdom of heaven explicit.
However, Christ also wants to make it clear that talking about the spirit as a "seed" doesn't capture every aspect of its nature. So he also likens in the leaven in dough, the treasure in a field, the pearl of great price, and a net caste into the sea.
The final parable is especially telling because it reshapes the Parable of the Good and Bad Sowers in an important way if you understand Christ's use of symbols. On the surface it seems to simple repeat the threat that the wicked will be punished. However, a closer analysis shows that it is not redundant but making a new and important point about the supremacy of the spirit.