Funny mail art envelope sent by Thérèse (France). See her blog to know her mail art and her calls (Among them, Funny Cows).
Another funny cow, in the shape of a folded postcard, sent by Heleen (the Netherlands).
The Laughing cow-related mail art sent by Suus in Mokum (the Netherlands). Also the back is interesting.
Postcard sent by Heleen (the Netherlands). I uploaded it to, maybe, too many albums: Orange Colour, Multiples on postcards, Food, Hearts... The back is also very interesting and orange: