Born in Genoa, in 1938 Mattei was expelled from all schools of the Kingdom of Italy for openly criticizing the Racial laws in class.

[1][2] Graduating in philosophy at the University of Florence in 1944,[3] she joined the partisans under the nom de guerre of Partigiana Chicchi.

[5][6] After the war, Mattei was a candidate for the Communist Party to the Constituent Assembly, in which she served as a bureau secretary.

[7] Mattei felt that the French symbols of IWD, violets and lilies of the valley, were too scarce and expensive to be used in poor, rural Italian areas, so she proposed the mimosa as an alternative.

[4][8][7] She died in Lari, Tuscany, aged 92,[7] the last living female member of the Constituent Assembly of Italy.