OK, this one is not a dahlia, but it's a super cool image, and the lily is also from my garden. The frames are flat black, and mats are white (note that you can frame with or without a mat! Note that adding frames and mat will make the overall piece larger by 4"-8" per side. See photos for reference.
Vivid Metals are a cool modern alternative. No frame or glass needed, and they come with their own mounting, floating about a half inch off the wall. The result is a high gloss image rich in colorwith outstanding clarity. They make a statement!