White, not black

I'm painting a picture frame for Abbey and I planned to use a black background.  My "black" is actually green-black because it's not as harsh and flat as black black.

However, I haven't been able to find green-black, so I'll use a white background.  Not actually white, but a very, very pale green-white.  Again, it's not as harsh and flat as white white.  Now I have to try out a new varnish that's not too shiny to coat the background before I begin painting the flowers.