White lilies are very frequently found in church flower displays. They are used for their symbolism. White represents purity in general and purity as it attaches to Mary, the mother of Jesus. It can also represent rebirth and consequently it is particularly found at Easter adjacent to the font and also near representations of the rebirth of Christ. This example in Tewkesbury Abbey caught my eye due to the vivid colours of the stamens.
photo © T. Boughen Camera: Nikon Z 5