I got a many to many user and role structure
users id name
roles id name
role_user
This should give you all users who are admins.
$users = User::whereHas('roles', function($q) { $q->where('name', '=', 'admins'); })->get();
You can see more information on the has() method at http://laravel.com/docs/eloquent#querying-relations
has()