It is always necessary to line a crochet bag to be used for shopping or books. If you put something heavier than a lettuce in a bag like this then the handles will stretch. Before you know it, the straps will be on your shoulder and the bag will be knocking the backs of your knees.
So, to prevent this, and to make it look nicer inside, then line it.
Sounds easy, and it is, but the difficult part for me is choosing an appropriate lining. This was the first one I thought of: a delicious ice cream parlour pink polka dot. Almost tempted to use it, but there is barely enough fabric, and I want to use it for something else.