I kept this bag simple by laying out the charm squares out in 9 rows of 4 squares. Without cutting up the squares, I just sewed them together as 5" squares.

After sewing all my charm squares together, I attached medium weight fusible interfacing to the back. The interfacing helps provide some stability to the bag. There are different types of interfacing available. I had medium weight on hand so that is what I used.
After fusing the interfacing, I quilted the patchwork piece with 1/4" stitching on each side of the all the seams. I also stitched 1/2" along the edges of the short sides of the piece. This created 1/4" quilt stitching along the back seam.

For my lining, I used a solid grey cotton I had on hand. I was hoping for something that had a denim look to it, but didn't find anything that I liked.
I decided I wanted to add an inside pocket to this tote bag, so after cutting the fabric to the size of my patchwork piece, I pressed a centre seam, and marked where I wanted to place the pocket.

To make the pocket, I cut out two pieces of fabric, and attached interfacing to one of the pieces.
I pressed a 1/4" flap at the top of each of the pocket pieces, and stitched the fabric pieces together along three sides, keeping the side with the flap unsewn. Leaving the top open allowed me to turn the pocket right side out, putting the interfacing on the inside. To ensure the bottom corners would turn out flat, I cut out the corners from the bottom. Once I turned the pocket right side out, I stitched the top of the pocket flap closed.

I placed the pocket flap in the marked box I drew on the lining, and attached it by sewing both sides and the bottom.
I sewed both the patchwork piece and the lining into a tube, by sewing the short sides together, with right sides facing in. This creates a back seam in the bag. In order to turn the bag right side out, I left a 4-5" gap in the back seam.

I laid each piece out with the seam centered, pressed the sides, and stitched the bottom of the bag closed. I did this for both the patchwork and the lining. After sewing the bottom, I cut out 2" squares from each of the bottom corners. To close the corners and create width, match the bottom seam up to the press line along the side, and sew the bottom corners closed.
For my straps, I used denim from an old pair of pants and cut two 6" by 30" strips. This worked out to be one leg of a pair of jeans, one strip from the front of one leg, and one strip from the bag. These strips created 1.5" width straps.
To create the 1.5" width, fold the 6" strips in half, and press to create a centre line. Open the strip, fold the sides into the centre line, and fold the strip in half along the pressed line. Stitch the straps closed along the long side.
Once my straps were made, I put the bag together by turning the patchwork piece inside out, pinning the straps on the inside of the patchwork, and sliding the lining piece in with right side facing the patchwork and the back of the lining visible if you look in the bag. I stitched the patchwork, straps and lining together by sewing a 1/4" around the top of the bag.

With the bag pieces sewn together, I turned the bag right side out, gently pulling the patchwork and straps through the 4-5" opening that was left in the lining seam. After turning the bag right side out, the opening in the lining is sewn closed. Once the bag was fully turned right side out, I sewed the opening in the lining closed, pressed the top of the bag where the patchwork and lining were sewn together, and then I stitched around the top of the bag 1/4" from the top seam.

This bag is bigger than a <a rel="noreferrer noopener" href="http://hereastitch.ca/rail-fence-patchwork-tote-bag/" target="_blank">rail fence tote bag</a> I made previously. I might use it as my day to day bag during work days. It could also be a good grocery bag. Hopefully some day soon I can use it.