Today, I doubt that generally people know where "La festa della donna" started from.
According to Wikipedia:
International Women's Day (IWD) is marked on March 8 every year. It is a major day of global celebration for the economic, political and social achievements of women.
If you continue reading, the website gives the historical origins of this commemoration:
The first IWD was observed on 28 February 1909 in the United States following a declaration by the Socialist Party of America.
The idea of having an international women's day was first put forward at the turn of the 20th century amid rapid world industrialization and economic expansion that led to protests over working conditions. By urban legend, women from clothing and textile factories staged one such protest on 8 March 1857 in New York City. The garment workers were protesting what they saw as very poor working conditions and low wages. The protesters were attacked and dispersed by police. These women established their first labor union in the same month two years later.
More protests followed on 8 March in subsequent years, most notably in 1908 when 15,000 women marched through New York City demanding shorter hours, better pay and voting rights. In 1910 the first international women's conference was held in Copenhagen and an 'International Women's Day' was established, which was submitted by the important German Socialist Clara Zetkin. The following year, IWD was marked by over a million people in Austria, Denmark, Germany and Switzerland. However, soon thereafter, the Triangle Shirtwaist Factory fire in New York City killed over 140 garment workers. A lack of safety measures was blamed for the high death toll. Furthermore, on the eve of World War I, women across Europe held peace rallies on 8 March 1913. In the West, International Women's Day was commemorated during the 1910s and 1920s, but dwindled. It was revived by the rise of feminism in the 1960s.
It is a tradition in Italy to give a yellow mimosa to women on the 8th of March. It is a beautiful scented flower, theat is in bloom early in Spring. Unfortunately this day si now becoming a celebration like Valentine's day, and the social and political reasons behind its historical origin are often forgotten.