Welcome to the board!
You have a lot of options.
You could machine sew them into a quilt, or take some and display them away from direct sunlight.
You can certainly use cotton backing- in fact I recommend it.
Is there any way you could post some photos? Other people will give you some ideas too. This board is very helpful.
I just thought of another thing- you could make pillows with some of the blocks as well. Or wallhangings of your favorite ones.