The answer is: Mark

Mark 4:26-29

The Parable of the Growing Seed is indeed tucked away in the Gospel of Mark, providing a unique glimpse into the Kingdom of God via an agrarian metaphor. Found in Mark 4:26-29, this parable succinctly illustrates God's sovereignty in the process of growth and development. Unlike some of the other Gospel writers, Mark often emphasizes the mysteries of the Kingdom in simple yet profound ways.

Here's a fun tidbit: this parable is only found in Mark, establishing a special identity for Mark’s Gospel. In this story, a seed is sown, and the farmer goes about his work, doing other things while the seed mysteriously sprouts and grows, whether the farmer understands how or not. It perfectly captures the marvel of life – things often happen behind the scenes that we can't control or fully comprehend.

Interestingly, this is a favorite among scholars who describe it as a beautiful reminder of patience in the spiritual life. Spiritual growth doesn’t demand instant results; it cultivates with time, just as it does in nature.

Reminiscent of other parables like the Mustard Seed, which follows closely in this chapter, each exploring growth's organic, sometimes unpredictable nature, they reflect a larger theme prevalent in all of Jesus’ teachings: faith as a slow-growing marvel in the heart. This encourages humility and trust in the natural unfolding of life’s journey. So, next time you plant a seed – physically or spiritually – remember it’s okay to step back and let nature take its course!