In popular fiction farmers will often grab pitchforks in an attempt to drive someone off. In my experience, while pitchforks are menacing, shovels are much more effective. In the instance of a mass of people needing to defend themselves with what they have at hand, what is the most effective hand tool/farming implement to use as a weapon? (Excluding actual pricey weapons of course)
Edit: apparently I was not clear enough on why the question related to worldbuilding. Hopefully now it's clearer that what people are likely to view as effective weapons are what get used and can widely affect possible outcomes of violent confrontations, and hence have a large impact on what details can be reflected in the fictional world. In addition, the availability of ideas in the answers below allows for a wider understanding to those not as familiar to said implements and the possibilities of improvised weapons. Also, folk heroes.