The Orthodox Church names this day Dormition of the Theotokos, also known in Eastern Orthodox world as Assumption Day or Holy Virgin Mary's Day, celebrated on August 15 each year.
It is is a name day for everyone named Maria, Mariana, Mara, Marcho, Mario.
Assumption Day is a great traditional feast. Votive offerings are made and sick people spend the night at "holy places" to gain health. A ritual bread, and the first picked and church-consecrated fruits of the season - water melons, grapes, honey - are given out for good health and richer harvest. The proverb says “Till Holy Virgin Mary’s Day straw turns into wheat, and after Virgin Mary’s Day – the wheat turns into straw!” - therefore good farmers should complete the threshing by Holy Virgin Mary's Day.
Until then every house makes a threshing-floor in the yard and traditionally it is round - so that evil forces do not affect the house. In the middle they set up the pillar – a thick post to which they tie the horses during threshing. Then they bring the sheaves from the field and put an unmarried young woman in the first cart but watch that she is not in her monthly period so that thewheat should remain clean. The man of the house feeds the oxen with "sporniche" - a special herb used for fertility. The woman of the house throws water from the well in front of the cart with a bucket decorated with a bunch of sweet basil, tied with a red thread, for the wheat to flow like water on the threshingfloor.
They grind the new wheat on Virgin Mary’s Day. They make ritual breads from that flour and it is believed that if rain falls on that day, the next year will be very prosperous. For the festive meal they kill an ewe, which is ritually fed and incensed, like the one at St. George’s Day. The liver of the animal is boiled and brought to the church to be sanctified. The meat is prepared on a spit on open fire, then the neighbors exchange meat and banitsa for health, saying: “Let Virgin Mary help you!”
In some regions, the day is also celebrated for the health of the oxen and, as on St. Vlasius’ Day, the woman of the house decorates their horns with buns, and feeds them ritually. Old legends advise to avoid touching anything red on that day to protect the cattle against bleeding and the young brides from barrenness. The festivities last till late at night.
More on the Dormition of the Theotokos day: Wikipedia