How about "tablescapes" rather than centerpieces? Battery operated christmas lights are available right now (they even have them with white stings, green stings, or even gold!) which would work for the illumination factor...(I have a friend who
used them for her outdoor, evening reception that restricted candles and it worked beautifully)...since you cannot use florals...how about some fabric? Some tulle or open weave fabric (I used
burlap on our tables as runners and it worked beautifully) with the lights woven in beneath?

I just checked your bio and it looks like you're drawn to a rustic look...
wheat or barley along the
table:
I did one wedding with potted gardenias as the centerpieces...they were in galvanized buckets and smelled heavenly. We ordered them from a garden supply in advance and placed them in a warm room for a few days before the wedding to
encourage the buds to open up.
This photo from Martha Stewart weddings:
What is your wedding date? Is it day or night? Formal, semi-formal? Let me know and I will run with some ideas and post some pics for you.
For now, here are MORE ideas...of the top of my head.
7 and 8 inch polyresin urns (unbreakable under normal circumstances), you could fill with fruit topiaries or feathers...peacock and ostrich would be oh so
glamorous! Tres chic!

And they have this version too in
7 and 12 inches:

Or spray paint them white or gold or silver or bronze or whatever color you like and insert a branch with little lights wrapped on it. You can also paint the branch (I did this in gold (sans lights) for a 50th wedding anniversary) or leave it
natural....mazanita branches are gorgeous for this! Use foam and plaster of paris to set the branches and then cover with sheet moss. Instant centerpieces!


This birch centerpiece is also a great idea (you can use battery operated votives or string lights instead of the candles)
Here's the how-to for the
Birch Centerpiece.
There also lots of options for
metal containers. Here's a small sampling:




These are called
Naked Wire L.E.D. Lights and the are battery operated and come in
a myriad of colors.
Here's another container option...
long, wooden planters...can be painted, stained or left as is...filled with nonfloral elements like
fruit and veggies, moss covered foam or...if you can get away with it...tall grasses.

You can also consider "edible" centerpieces...my BFF had mini-wedding cakes on each table at her outdoor, rustic wedding. Along with those she had "Martha Stewart Tissue Flowers" anchored on the tables with ballon bouquet weights that she got from
the party store:

I also attended a great wedding where all of the food was served "family-style" from the center of the table...it was AWESOME! They used levels in the middle of the table (I think just various pedestals and also small boxes under fabric) to place
the food on. It was similar to something like this:

I also have made edible topiaries with a cabbage and strawberries. You take a straight branch, make the top into a point, clean it up, anchor it in a container
(like the urns above) with foam and plaster of paris...take a small cabbage and spear it onto the pointed top of the branch (think like a pig, thick toothpick), attach strawberries all over the cabbage with toothpicks in the stem area of the strawberry
and then poked into the cabbage. It' SUPER cute, unexpected and edible. Here's a similar idea without the stick:

You could do this with small citrus fruit (lemons,
limes, mandarin oranges, etc. I would say pick one fruit for each topiary for maximum impact. I have also seen these made on foam ball forms with nuts such as walnuts.
These are made with faux fruit and you can order them
HERE.

This pretty too and super easy to DIY.


And of course you can do cupcake trees on each table as
the centerpiece.


See how it was all pulled together
HERE.

Here's another cute idea from
Martha Stewart Weddings...centerpieces that feature little wrapped favors displayed on a pedestal...practical
and great looking!

Finally, you can use colored linens on the tables to spice them up and add some color.