Cheryl,
I don't know about growing mimosa in your area (I am in Mississippi, zone 8b). I would warn you against that tree though. Even though the leaves/flowers are pretty, these trees once established are very prone to splitting. The wood is simply not hard enough, not flexible enough, to support their long limbs. I also will warn you that their roots are shallow and very invasive. You don't want one close to your house. Since they have these shallow roots, when the soil becomes saturated and there is strong wind, these trees will topple. Also those extremely long, shallow roots always will grow new plants, even when the tree itself has broken down or blown down. Digging those roots up is a real chore.
This information is all from my decades-long experience with these trees. Though they grow fine here, I would never grow another one. When I was growing up it seemed like there were mimosa every where. Now I seldom see one. I am sure others will have different experiences and opinions.
