If you follow Rabbinic reckoning, the second of the great festivals prescribed by Torah, the Festival/Feast of Weeks/Harvest otherwise called the Day of First-fruits, has now begun! The Mishnah and its Babylonian or Jerusalem Gemarah refer to it as Atzeret (meaning Solemn Assembly). Most Christians call it Pentecost.
Three times in the year you must make a pilgrim feast to me…observe the Feast of Harvest, the first fruits of your labors that you have sown in the field…
Exodus 23:14, 16, NET
You must observe the Feast of Weeks – the first fruits of the harvest of wheat –
Exodus 34:22, NET
You must count for yourselves seven weeks from the day after the Sabbath, from the day you bring the wave offering sheaf; they must be complete weeks. You must count fifty days – until the day after the seventh Sabbath – and then you must present a new grain offering to the Lord. From the places where you live you must bring two loaves of bread for a wave offering; they must be made from two tenths of an ephah of fine wheat flour, baked with yeast, as first fruits to the Lord. Along with the loaves of bread, you must also present seven flawless yearling lambs, one young bull, and two rams. They are to be a burnt offering to the Lord along with their grain offering and drink offerings, a gift of a soothing aroma to the Lord. You must also offer one male goat for a sin offering and two yearling lambs for a peace offering sacrifice, and the priest is to wave them – the two lambs – along with the bread of the first fruits, as a wave offering before the Lord; they will be holy to the Lord for the priest. On this very day you must proclaim an assembly; it is to be a holy assembly for you. You must not do any regular work. This is a perpetual statute in all the places where you live throughout your generations.
Leviticus 23:15-21, NET
Also, on the day of the first fruits, when you bring a new grain offering to the Lord during your Feast of Weeks, you are to have a holy assembly. You must do no ordinary work. But you must offer as the burnt offering, as a sweet aroma to the Lord, two young bulls, one ram, seven lambs one year old, with their grain offering of finely ground flour mixed with olive oil: three-tenths of an ephah for each bull, two-tenths for the one ram, with one-tenth for each of the seven lambs, as well as one male goat to make an atonement for you. You are to offer them with their drink offerings in addition to the continual burnt offering and its grain offering – they must be unblemished.
Numbers 2826-31, NET
You must count seven weeks; you must begin to count them from the time you begin to harvest the standing grain. Then you are to celebrate the Festival of Weeks before the Lord your God with the voluntary offering that you will bring, in proportion to how he has blessed you. You shall rejoice before him – you, your son, your daughter, your male and female slaves, the Levites in your villages, the resident foreigners, the orphans, and the widows among you – in the place where the Lord chooses to locate his name.
Deuteronomy16:9-12, NET
When you enter the land that the Lord your God is giving you as an inheritance, and you occupy it and live in it, you must take the first of all the ground’s produce you harvest from the land the Lord your God is giving you, place it in a basket, and go to the place where he chooses to locate his name. You must go to the priest in office at that time and say to him,
I declare today to the Lord your God that I have come into the land that the Lord promised to our ancestors to give us.The priest will then take the basket from you and set it before the altar of the Lord your God. Then you must affirm before the Lord your God,A wandering Aramean was my ancestor, and he went down to Egypt and lived there as a foreigner with a household few in number, but there he became a great, powerful, and numerous people. But the Egyptians mistreated and oppressed us, forcing us to do burdensome labor. So we cried out to the Lord, the God of our ancestors, and he heard us and saw our humiliation, toil, and oppression. Therefore the Lord brought us out of Egypt with tremendous strength and power, as well as with great awe-inspiring signs and wonders. Then he brought us to this place and gave us this land, a land flowing with milk and honey. So now, look! I have brought the first of the ground’s produce that you, Lord, have given me.Then you must set it down before the Lord your God and worship before him. You will celebrate all the good things that the Lord your God has given you and your family, along with the Levites and the resident foreigners among you.Deuteronomy 26:1-11
The Rabbis limit what produce and agriculture specifically apply to The Festival to that elucidated in Deuteronomy 8:8:
First-fruits may be brought only from the seven kinds…
Mishnah, Bikkurim 1:3
For the Lord your God is bringing you to a good land…a land of wheat[1], barley[2], vines[3], fig[4] trees, and pomegranates[5], of olive[6] trees and honey[7]…
Deuteronomy 8:7-8
This limitation was not entirely followed. Some augmented that produce with others not enumerated (Mishnah, Bikkurim 3:9-10).
The Oral Law gives us a glimpse into how the people set apart their produce:
How do they set apart the First-fruits? When a man goes down to his field and sees [for the first time] a ripe fig or a ripe cluster of grapes or a ripe pomegranate, he binds it round with reed-grass and says,
Lo, these are First-fruits.Mishnah, Bikkurim 3:1