I had a picture frame and a nice picture, but no mat. I wanted a textured look to coordinate with another picture in the same area. I'm not trying to be matchy-matchy but I like to coordinate. I have also been very attracted lately to burlap and things with texture. I had some leftover burlap and another bit of fabric which is more linen-like, and chose the latter.
You can cut a mat from a cereal box or buy one.
Have some glue on hand, by the way I like Elmer's and am not a paid advertiser.
I cut the material and then cut a coordinating square in the center, making four slits in corners. Spray the mat with glue and place the mat onto the fabric. Then fold the center onto sides after running glue stick.
Here's what it look likes.
To fold over corners, then cut a small square off, which will help it fold flatter.
Once dry, place in frame and place your picture
and you are finished.
A new look without huge time or cost.