I'm not sure if most are into terrariums.. but I am! And hopefully the guests at the shower that I'm working on are as well. ;-) They come in all shapes and sizes, and can be a bit organic and earthy looking, but I plan on softening up the look with a touch of baby. I hope this works out. So, here are some inspiration for centerpieces.
Green Wedding Shoes
Etsy shop Augury