A Herd of Cows, a Gaggle of Geese, and a .....

So we've been making a custom order that consists of a grundle of beaver finger puppets (the second from the left).  That fact alone made my mind start thinking -- I know, a scary thought.  Some animals I quickly recognize their collective term.  For example, a swarm of bees, a flock of birds, a herd of cows, and a gaggle of geese.  But off the top of my head, I couldn't think of what a group of beavers would be called.  So how about you?  Do you know it?  And I mean without the help of the Internet because that would of course be cheating.  If you do, go ahead and share in the comments.