Traditional options:
* A ring/circle/court of fairies - Emphasizes their magical nature and social structures.
* A host of fairies - Emphasizes their numerous and ethereal nature.
Creative options:
* A shimmer of fairies - Evokes their delicate and glittering presence.
* A whisper of fairies - Suggests their quiet and magical nature.
* A swarm/flight of fairies - Emphasizes their movement and lightness.
* A bloom/bouquet of fairies - Connects them to the beauty and fragility of nature.
Ultimately, the best collective noun depends on the specific context and the desired effect. You can even be creative and come up with your own!