The dress reminds of of Little House on the Prairie!  Look at the high neckline and collar and the long full sleeves!

Apparently, though, it's a coveted Valentino gown in a fabric printed with dandelions that was recently seen on the runway, and speculation was who was going to be the one to get to wear the dress.  According to a StyleBistro.com article, some thought Anne Hathaway or Keira Knightley would wear the dress to an event.  It was a surprise that it ended up being Amber Heard who wore the gown, especially since she normally dresses in very tight-fitting, backless, sexy gowns. 

This closer-up photo shows more of the detail on the front of the bodice of the gown, including the little Peter Pan collar, as Amber heads into the Art of Elysium after party.
http://www.zimbio.com/photos/Amber+Heard/Audi+Presents+Art+Elysium+6th+Annual+HEAVEA-ßhUxldbqVNE

Love pirates & mermaids?  Visit my Zazzle store at http://www.zazzle.com/PiratesQuarters 
For a trip down memory lane, visit my vintage store at http://www.zazzle.com/AsTimeGoesBy