I'll go... Then you...
1) Engagment ring... recycled gold, ethical sapphire. (Liza Shtromberg, LA)
2) Small number of seasonal flowers from a local farmer.
3) Locally sourced food from a local caterer.
4) Keeping the vendors and decorations to a minimum (using mom's canning jars) and things that are in the 'rent's barn.
5) Recycling mom's dress from the 70s into a reception dress, sans sleeves that have since turned brown.