Chuseok (Kor. 추석, Chin. 秋夕) refers to the harvest festival celebrated on the fifteenth day (the full moon day) of the eighth lunar month. Chuseok literally means “autumn evening,” and may be understood to mean the “autumn evening with the brightest moon.”

In traditional agrarian society, the Chuseok season was a time for farmers to relax and enjoy the fruits of their hard labor. According to a proverb, “A farmer in May is a philosopher in August;” this saying refers to the fact that farmers have no respite in May but can rest in August. When the season’s toil is over and the pace slows down in rural communities, farmers can enjoy their free time.

Chuseok is also a season of thanksgiving as Koreans observe charye (Kor. 차례, Chin. 茶禮, lit. tea offering ceremony, an ancestral memorial service) at home and visit their ancestral graves. Usually people visit these ancestral grave sites several days before Chuseok in order to remove weeds that have grown there over the summer. The day of the festival starts with preparing an offering table with newly-harvested rice and seasonal foods for the ancestral memorial service. The offerings must include bite-size rice cakes stuffed with sweet fillings known as songpyeon (Kor. 송편, Chin. 松餠, lit. pine needle rice cake). Families proceed to the ancestral tombs after this memorial service. The tradition of worshipping four generations of ancestors during the charye ceremony dates back to the late Joseon period (17th century - 1910).

Songpyeon is the most representative dish of Chuseok, just as tteokguk (Kor. 떡국, lit. rice-cake soup) is for the Lunar New Year. Other dishes prepared for the ancestral memorial service on Chuseok include toranguk (Kor. 토란국, Chin. 土卵-, taro soup), hwayangjeok (Kor. 화양적, Chin. 花陽炙, skewers with young mushrooms, balloon flower roots and beef), and nureumjeok (Kor. 누름적, skewers with flour- or egg-coated vegetables and meat). All of these dishes are eaten by family members and shared with relatives and neighbors after the memorial service.

The full moon in the agrarian society was an important symbol of prosperity and fertility, and the full moon on Chuseok was associated with ripe plants full of grain. The alternating lunar phases – from the waxing crescent moon to the full moon, and from the waning crescent moon to the new waxing crescent moon – were considered to be a vital cycle similar to the farming cycle. Accordingly, the vitality of the universe was thought to reach a pinnacle on the day of the full moon. Consequently, the day of the full moon in the middle of the harvest season, Chuseok, had a special significance for farming communities.

https://myhubs.org/2015/10/05/on-the-korean-traditional-holiday-chuseok/

One of the major foods prepared and eaten during the Chuseok holiday is songpyeon (송편), a Korean traditional rice cake which contains stuffing made with ingredients such as sesame seeds, black beans, mung beans, cinnamon, pine nut, walnut, chestnut, jujube, and honey. When making songpyeon, steaming them over a layer of pine-needles is critical. The word ‘song’ in songpyeon means a pine tree in Korean. The pine needles not only contribute to songpyeon’s aromatic fragrance, but also its beauty and taste. Songpyeon is also significant because of the meaning contained in its shape. Songpyeon’s rice skin itself resembles the shape of a full moon, but once it wraps the stuffing, its shape resembles the half-moon.

Another popular Korean traditional food that people eat during Chuseok is han-gwa (한과). It is an artistic food decorated with natural colors and textured with patterns. Hangwa is made with rice flour, honey, fruit, and roots. People use edible natural ingredients to express various colors, flavors, and tastes. Because of its decoration and nutrition, Koreans eat hangwa not only during Chuseok, but also for special events, for instance, weddings, birthday parties, and marriages.