A little white dress is always a good idea especially if a denim piece serves as a jacket. The look has a casual vibe because of the shirt even though this dress can be wear it in more different color combinations or simple without no layers for a Summer wedding party.
Endless possibilities with a LWD.
Denim shirt: American Eagle/ option Here and Here
Dress: c/o Three Modern Muses/ Here
Bag: Costume National
Sunglasses: Prada/ option Here and Here
Samdals: Zara/ similar style Here, Here and Here