The day following the weekly Sabbath during the week of Unleavened Bread is called the Feast of First Fruits. It always falls on Saturday evening to Sunday evening. This holiday celebrates the beginning of the barley harvest. It is a perpetual statute (Lev. 23:9-22).
First Fruits is not widely celebrated in Judaism. In fact, most Jewish people would probably associate first fruits with Shavuot, or Pentecost if you asked them about it. The feast of Passover/Unleavened Bread takes much precedence in Jewish culture. Since First fruits always falls during the week of Unleavened Bread you don’t find most Jewish people observing it.
It is probably most widely celebrated by Messianic Jewish congregations and other Torah-observant groups. The reason for this is that we look to the Bible for our holidays and we also know Yeshua as our Messiah. And the Bible shows us that Yeshua fulfilled the feast of First fruits when he rose from the dead (1 Cor. 15:20 -28). This important connection gives us all the reason we need to celebrate!