From one who has made many rail fence quilts, this is my opinion.
A small inner border of ANY fabric used within the blocks does not work well, because all of them touch the edge of the top at some point, and therefore, "bleed" into the border.
The best small inner border (I call these "stopper" borders because they "stop" the action) is a fabric that contrasts with the colors in the top. Note the graphic below for an example.
In your case, something in the yellow/gold/mustard family would be wonderful. Remember that you will need only a little of this for it to work....a border that finishes about 1" - 1 and 1/2" is good.
Then, I usually use a wide outer border in a large scale print that incorporates the colors of the rail fence. There are lots of them out now in red/white/blue.
The reason I use a large print? I was told by a wise teacher years ago that when the block is simple, when you are not doing the work (of jazzing up the quilt with fancy piecing), then the fabric has too. That quote has often served me well, wish I had a picture to show you!
Jan in VA
In this case, the red is the stopper border for a blue and yellow quilt.
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