Adam Clarke on Song of Solomon 7:2

Thy navel is like a round goblet - This may also refer to some ornamental dress about the loins. These suppositions are rendered very probable from hundreds of the best finished and highly decorated drawings of Asiatic ladies in my own collection, where every thing appears in the drawings, as in nature.

A heap of wheat set about with lilies - This is another instance of the same kind. The richly embroidered dresses in the above drawings may amply illustrate this also. Ainsworth supposes the metaphor is taken from a pregnant woman; the child in the womb being nourished by means of the umbilical cord or navel string, till it is brought into the world. After which it is fed by means of the mother's breasts, which are immediately mentioned. Possibly the whole may allude to the bride's pregnancy.