Weddingbee boards

Hi everyone! I'm having a Jewish wedding with a traditional chuppah (wedding canopy). My fiancé and I (and his dad) have DIY, and I'm looking for some help figuring out one of the last decorative pieces.

It is made of 4 large flower pots as the bases for the 4 poles. We put cement and PVC pipe in the pots to act as a stand for each of four wooden poles that will slide in. Fabric will be attached to the top of all 4 poles.

Here's where you come in: The pots are only half-full. I need to fill the pots the rest of the way with something so that when someone looks at it from the top down, it will look pretty and so they won't be looking at the ugly cement. I don't want to do anything too elaborate, but I need to figure out what to use to fill it. I had been thinking about buying fake moss for the top, but what can i use to fill the space between the top of the cement and top of each pot?

I'm going to do my best to include a picture of one of the half-full flower pots, as well as an example of what the finished product will basically look like (though I don't want to use ivy at the base, nor will I wrap anything around the poles like in the photo).

Thanks to @julies1949 and @rileyjane for the grest suggestions! I definitely want to try and keep the filler on the lighter side, since each already weighs about 30-40 lbs!