"The Lily of the Valley" is an epithet for the Blessed Virgin. In simply describing this May flower we can see a few attributes of Mary.
The lily, with its white petals, symbolizes purity. The Easter Lily's flower, atop the straight stem (honesty), is in the shape of a trumpet, pointing up to heaven, as if it is announcing the good news of the Resurrection. But it is also in an open position, able to receive the gifts and love of God. Inside the flower are seven gold (in some cases, red) seeds. The seven sacraments and gifts of the Holy Spirit come from God. And in connection to purity, the red seeds symbolize the fire of love for God that burns within the virgin's heart. The Blessed Virgin is no shrinking violet. She is a burning bush.
The posture of lily of the valley species is slightly different. The bell-shaped flower on the wilted stem points to the ground, symbolizing a teardrop and the virtue of humility. Mary, in saying "I am the handmaid of the Lord," has no ounce of pride.
The lily is the first of the spring flowers to bloom, sprouting from the cold earth around March 25th (the Annunciation). These hardy and fragrant perennials grow abundantly, rapidly and in any environment, be it a valley, plain, manicured garden or a wild field. Wherever they be, they beautify the landscape. Hosea, prophesying the growth of Israel, said, "he shall grow as the lily, and cast forth his roots as Lebanon" (Hosea 14:5).
"Consider the lily of the fields," Jesus himself told us. "Even Solomon in all his glory was not arrayed like one of these" (Matthew 6:28-29). We should consider Mary, the Lily of the Valley and greatest flower of all.