Another custom is eating cheese, with many symbolic meanings.

Shavuot was one of the three harvest festivals, when we brought offerings to Jerusalem. It was the only festival which did not have an event or commandment from Torah associated with it, so later on the rabbis decided to associate it with the giving of the Torah on Sinai, which makes sense since Pesach was only seven weeks before. This is what happened when we still had a Jewish nation:

All [the inhabitants of] the cities that constituted the selected group going to Jerusalem assembled in the city... and spent the night in the open place without entering any of the houses. Early in the morning the officer said: ‘let us arise and go up to Zion, to the house of the Lord our God.'

Those who lived near (Jerusalem) brought fresh figs and grapes, but those from a distance brought dried figs and raisins. . . .

The governors and chiefs and treasurers [of the temple] went out to meet them. All the skilled artisans of jerusalem would stand up before them and greet them: ‘brethren, men of such and such a place, we are delighted to welcome you.' The flute was playing before them until they reached the Temple Mount; and when they reached the Temple Mount even King Agrippa would take the basket and place it on his shoulder and walk as far as the temple court. . . . . while the basket was yet on his shoulder he would recite from: ‘I declare this day to the Lord your God,' until the completion of the passage. . . . he then recited from ‘a wandering Aramean was my father' until he completed the entire passage. He would then deposit the basket by the side of the altar, prostrate himself, and depart.

Originally all who knew how to recite would recite while those unable to do so would repeat it; but when they refrained from bringing (because they were embarrassed to admit that they didn't know the passage by heart), it was decided that both those who could and those who could not [recite] should repeat the words.