This special species probably can`t be used as Bonsai. It died back every year, so no trunk. But it is worth while as undergrowth in a bonsai setting.
A friend of mine grew it for three years outside. In his situation it was very small leafed, compared with M.pudica.
What I want to try with M.nutallii is to grow it on my islands outside. If this works well I will give another friend some for his Bonsai forest setting.
The other species of this genus are sadly not frost hard at all. And the plants I had from Mimosa pigra died of neglect after some years. Would be worth a try.
I had given the rest of the seeds to our Botanical Garden, but they don`t have any plants now. But this species is a Neophyte in most frost-free parts of the world.