OHHHH I see okay, I have never seen a mailbox cover ever, then.
I think I have seen pennants, but not for sports, some people have a little flag usu. square jutting off the porch or so and often they have Winnie the Pooh or Snowmen at Christmas etc. on them.
I am happy for Trippi, I too had a fav. blanket growing up it was an event for my Mother to wash it :))))