It would have actually been a pretty lavish meal. It was Pesach. That means it was the "seder" for Passover, the communal dinner to celebrate that Feast day. It is the only feast day that is celebrated, to this day, at home. That is, in someone's home or homelike setting. A Passover Seder is one of the primary Feasts (MoAdim) Moshe (Moses) laid out in the Torah, that is the first 5 books of what is now called the Old Testament scriptures (of the Jews, Messianics and Christians).
Jews (remember, Jesus was a Jew and was then still in complete obedience to the Mosaic law) saved up all year, and many still do, for that feast meal. Family came from all around, even other lands, and it was one of 3 "pilgrim" feast days in that the adult males had to go to Jerusalem to observe, if they could. That's why Jesus had someone go and find the man who had "prepared" for them "the meal." Passover is always done with matzah and wine. Matzah is just the hebrew word for unleavened bread. Y'shua (Jesus) served that day and the next as "'the Lamb of God" who takes away the sins of the world,'" just as John the Baptizer said of him, and also as the First Fruits (of the New Covenant). See Hebrews 13:11-16:
The high priest carries the blood of animals into the Most Holy Place as a sin offering, but the bodies are burned outside the camp. 12 And so Jesus also suffered outside the city gate to make the people holy through his own blood. 13 Let us, then, go to him outside the camp, bearing the disgrace he bore. 14 For here we do not have an enduring city, but we are looking for the city that is to come. 15 Through Jesus, therefore, let us continually offer to God a sacrifice of praise—the fruit of lips that openly profess his name. 16 And do not forget to do good and to share with others, for with such sacrifices God is pleased.