I think that Forever 21 has seriously improved their game lately with the diversity of items they're offering ... you didn't used to see dresses like these there very often.
My latest favorites ...
This polka dot belted skater dress
This abstract pattern lace dress
This printed tie collar dress
This cutout neckline belted dress
This pleated flounce trim dress
This polka dot daytime dress
This belted skater dress
This studded collar a-line dress
PS - they'll ship orders of $50 or more to you for free.