On the Lord’s Day of the Lord gather together, break bread and give thanks, after confessing your transgressions so that your sacrifice may be pure. Let no one who has a quarrel with his neighbor join you until he is reconciled, lest your sacrifice be defiled. For this is that which was proclaimed by the Lord: “In every place and time let there be offered to Me a clean sacrifice. For I am a Great King,” says the Lord, “and My name is wonderful among the gentiles.”
The Didache was written before 140 A.D., – the writer (who is unknown) is likely a contemporary of the Apostles.
**Justin Martyr First Apology 67. **( - written about 150 A.D.)
On the day which is dedicated to the sun, all those who live in the cities or who dwell in the countryside gather in a common meeting, and for as long as there is time the Memoirs of the Apostles (NT canon was only set in 395 A.D.) or the writings of the prophets are read. Then, when the reader has finished, the president verbally gives a warning and appeal for the imitation of these good examples. Then we all rise together and offer prayers, and, as we said before, when our prayer is ended, bread is brought forward along with wine and water, and the president likewise gives thanks to the best of his ability and the people call out their assent, saying the Amen. Then there is distribution to each and the participation in the Eucharistic elements, which also are sent with the deacons to those who are absent. Those who are wealthy and wish to do so, contribute whatever they themselves care to give; and the collection is placed with the president . . .
For 2,000 years the mass has hardly changed. We just probably have the collection earlier in the Mass rather than at the end.