Back when I first learned to quilt and didn't know enough to know I was doing it "wrong"...my first quilt was a Turning Twenty Again king size quilt for my bed. Into the project, Decided I wanted scalloped border on it. I made the border with two layers of fabric about 15" wide,right side together, batting on one side. Marked out the scallops to fit the completed top, stitched the scallops on the border, trimmed, clipped seams and turned so I had a layered scalloped border with an open raw edge that I simply sewed to the finished top (that needed binding). It went on kinda like a big binding. Worked beautifully and I was very proud. Only later did I learn that was NOT the way to do it.
But it worked for me and if I decide to put a scallop border on another quilt, I will do it the same way again.
I do not listen to the quilt police!