This is a cool older piece, I have no idea where or when it was made.
It feels old to me, 20's 30's? perhaps.
It feels American to me, doesn't feel like Murano or Chinese.
Bottom is unsigned, and unmarked. The base is sightly concave (after a ledge of about 1/2").
I describe the shape as a barrel.
It has three levels the ground is frit, with some glistening, possibly very soft aventurine mixed in, (perhaps Murano after-all). The middle layer is a many petaled blossom.There is a perfect circle of good sized bubbles, directly under the petals, roughly half way between the ground and the flower. And of course the top layer is an almost completely flat butterfly, just a tiny bit of curvature.
Okay gang, go to it. I paid very little ($15 American), so won't be crushed if it's a somewhat worthless piece.