I used various red, white, and blue cotton fabric and denim; some recycled from my husband's old jeans, and some new. I used 7" squares and sewed a red X through each "sandwich" of denim, white flannel, and 100% cotton top. I found these sandwiches to be rather thick and heavy. Next time I will omit the flannel if it's a denim rag quilt. I used a 1/2" seam allowance to give enough room for the fraying. LOVE it when it comes out all frayed from the dryer! My dryer lint tray was mighty full of fluff. I cleared it every 10 minutes.
I find it much easier to cut the denim when it comes off the bolt from the fabric store rather than try to get random pieces from different pants. But I do like the color variation and rugged look of various used denim jeans. The front is made from denim off the fabric bolt and the back is mostly recycled jeans.
True to the red, white, and blue pattern on the front but completely random-placed denim on back. (I didn't even look at the back as I pieced the front.) I like to add a block with a pocket to give it character. Plus it makes a nice place to store candy wrappers or a boogey kleenex. :)
Happy Independence Day!