Leviticus Lev 23:15–22
The Torah commands one feast by counting: seven sabbaths plus one day, from the wave-sheaf of Passover week to the leavened loaves of the fiftieth day. The count matters. The leaven matters. When Acts 2 dates the outpouring of the Spirit to this feast, every detail is already in the book of Leviticus.
Matthew 13:31-46
In the Sower, birds correspond to the evil one. Every other metaphorical use of leaven in the NT is negative. And in every redemptive use of 'purchase,' Christ is the buyer. When you apply the keys Jesus gave in the explained parables to the ones He left unexplained, the standard readings don't survive.