Yes, they can be decorative and/or functional ... bird feeder, plant stand, side table, birdbath, gazing ball stand, topped with a small piece of statuary ... ??
Ooo, ooo, Robin ... love the vintage white opalescent glass one on the bottom!!
They don't have to be made from glass objects but one thing I've found is that some glazed plates, dishes, vases and pottery will crack due to the stresses of weather. I don't object to that myself as long as they remain solid and stable. If you are using them to hold water as a birdbath or bird watering station, that can be a concern. I try to keep my pottery stacks under at least a bit of protection like carport, trees, etc.
