The Kingdom of God

What shall we say the kingdom of God is like, or what parable shall we use to describe it? It is like a mustard seed, which is the smallest of all seeds on earth. Yet when planted, it grows and becomes the largest of all garden plants, with such big branches that the birds can perch in its shade. (Mark 4:30-34)
However the coming of the kingdom of God is not something that can be observed, nor will people say, ‘Here it is,’ or ‘There it is,’ because the kingdom of God is in your midst. (Luke 17:20-21)