However, you could use a general term for groups of people performing, such as:
* A troupe of Morris dancers
* A company of Morris dancers
* A team of Morris dancers
* A set of Morris dancers
You could also be creative and use a descriptive term related to Morris dancing, such as:
* A jig of Morris dancers
* A ribbon of Morris dancers (referencing the ribbons often used in Morris dancing)
* A bell-ring of Morris dancers
Ultimately, the best collective noun will depend on the specific context and the desired effect.