Here is a pattern for a heavy string grocery sack that's works up quickly. All you need is fine cotton cloth torn into thin strips to make it up, or you can use heavy string or a cotton yarn. You could also use jute or hemp cord. make several of these to take to the grocery store rather than use bags.

Preparation:
Use fine shirt weight cotton rags, and tear into thin strips. These strips need to be so thin they are like a heavy yarn when compressed. Over lap genrously, and sew together. Roll into balls in preparation for making the bag.

Materials:
Heavy cotton string, sugar and cream type cotton yarn, or thin rag strips
K crochet hook

Directions:
Bottom of Sack Chain 20 stitches.
Row 1: chain 2 double crochet across Row 2-20: Repeat Row 1.

Sides Row 1:Chain two and begin to double crochet around the the outside edge of the whole bottom section. Row 2 -until length is met: Chain six skip over five stitches and double crochet. Continue in this manner until you achieve the length you want.

Handles To make handles single crochet in top edge and then chain 22 stitches. Stretch handle to comfortable length and then single crochet into top edge to secure.

Great!

Now you have a wonderful eco sack for groceries or the beach!