Albert Barnes on Matthew 13:8

Into good ground. The fertile and rich soil. In sowing, by far the largest proportion of seed will fall into the good soil; but Christ did not intend to teach that these proportions would be exactly the same among those who heard the gospel. Parables are designed to teach some general truth; and the circumstances should not be pressed too much in explaining them.

An hundredfold, etc. That is, a hundred, sixty, or thirty grains, for each one that was sowed--an increase by no means uncommon. Some grains of wheat will produce twelve or fifteen hundred grains. The usual proportion on a field sown, however, is not more than twenty, fifty, or sixty bushels for one.