Ullambana, happy are those who wear rosy flowers on their shirts
For the Vietnamese Buddhists, when going to pagodas on this day, the people whose mothers are still living wear a rosy flower on their shirts, but those whose mothers are dead wear a white one.
However, the custom is not Vietnamese tradition; and even the Ullambana ceremony is not universal for all Buddhist denominations. The wearing of flowers to pay honor and gratitude to one's mother is an adopted custom, originated from Japanese. This is attributed to a Vietnamese Zen-Buddhist monk, Thích Nhất Hạnh by the Dharmanym, who after the trip to Japan in early 1960's brought home the custom of Buddhist on Ullamban. Then the Unified Associates of Vietnamese Buddhism launched a campaign to adopt this practice into Buddhist ritual practice in Vietnam.
The Ullambana, also known as Ghost Festival, has another story, originating from the Ullambana Sutra (known as Kinh Vu Lan in Vietnamese). In the Sutra, the Buddha (Gautama) gave a brief discourse to Monk Maudgalyayana (Mục Kiền Liên) about the filial piety, instructing him to offer food and clothes to the Shangha on the 15th of the 7th month so that his mother from the low realm could be liberated and reborn into the human realm again.
Whatever all these are derived from, the result is that Buddhists today have some humane civilized cultural customs to practice. Blessed art Thou on Ullambana! Sadhu!