We do not know with any specificity who the first people to develop agriculture were. In other words, we do not have a name for them or anything like that. All we really know for sure is where those people lived. So far as we know today, the first people to domesticate plants were people who lived in the Fertile Crescent. This is an area that is now in countries like Iraq, Syria, and Israel. We know that people in the Fertile Crescent domesticated things like wheat, peas, barley, lentils, and olives by 8,500 BC.
At that time, there were no civilizations to lend their names to the people who first developed agriculture. The first civilization was Sumer, which was established in Mesopotamia. However, the people who first developed agriculture cannot be called Sumerians as Sumer was not occupied until at least 4,000 years after agriculture was developed.
Thus, we do not have a name for the people who developed agriculture, but we do know that they lived in the Fertile Crescent.