Granny Square Bag

For the main body of the bag make 2 granny squares, here is a basic granny square pattern:

Ch 6 , slst in 1st ch to make a circle. 

Rnd 1: ch 3, dc 2 in loop.  *ch 3, dc 3 into loop* repeat from * 2 more times, ch 3 more and slst to first ch 3 starting ch.

Rnd 2: (2nd color) Start in corner, ch 3, dc 2, ch3 dc 3, ch1.  In next corner *dc 3, ch3, dc3, ch1*  Repeat from * 2 more times, slst last ch1 to the first ch3 starting ch.

Rnd 3: (1st color) Start in corner, ch 3, dc2, ch3, dc3, ch1. * In ch3 sp dc3, ch1.  dc3, ch3,dc3, ch1 in corner*  Repeat from * 2 more times, slst last ch1 to ch3 starting ch.

Rnd4 & 5: Continue with pattern, using 2nd color.
Rnd6: ch 1 sc around, slst at begining ch 1. 
Rnd 7: ch 2, hdc around, slst at begining ch 2, fasten off. (with second square I inverted the colors and dont fasten off until you slst the two pieces together leaving one side open)

Strap
I just made it as long as needed for me.  So just ch as many as you need, then turn and hdc in 3rd ch from hook all way to end, then ch 1 turn and sc across to end, slst to bag, fasten off.  Sew other end to bag where you want it. 

If you want, add a liner of fabric and zipper or button, if not your done!