I am honestly thinking about working actively on this problem. Right now, the information is spread out across several websites and databases. The best way that I have discovered is to find local to your state organizations that serve as stewards for native plants. At least in my state, there are at least three, and these places are normally non-profit organizations that also sell the native plants which are also grown in your state, making them a great choice. We just got our house last year and a yard to go with it, and it's my plan this year to go along with these local organizations to purchase all my native plants. I use the app Picture This to identify plants that are currently in my yard to know which ones I want to remove and replace with native plants. The app will often tell you where the plant is native to, and if not, I research it online.