These are glass stones or beads that I use in the bottom of my vases. They just add a touch of 'je ne sais quoi', sparkle and also raise the flowers if the stems are too short.
I haven't actually got any flowers and think I might just have to pop out and get some.
This is lovely Cazzi... I keep a pair of clippers on my Jeep rides and often cut wildflowers (aka weeds) and grasses along the roadside... I take them home and put in vases... beautiful to me and they are free.
I really like how you used the vase to surround those stones. I have a similar style cut glass vase and will have to copy this style at some point in the future.