There were plenty of agricultural societies that were also fairly egalitarian. One interesting bias we tend have is that we identify "advanced" societies by how much they look like our own. This leads to a general bias towards deeply hierarchial, stratified societies being described/perceived favorably in media against their less familiar neighbors.
The ones I was specifically thinking about were the Puebloans of the American Southwest. There's a famous old paper whose title summarizes the situation pretty well:
"Although they have petty captains, they obey them badly"
