I have harvested the first lettuce. You can see the lettuce on the chopping board in the picture below. It was very green and crispy, and much nicer than the lettuces you buy in shops. Please note that these are baby lettuces which can be grown in window boxes; that's why it's not very big.
There are several more lettuces which are ready to be harvested, and then other ones which are smaller and will provide food later in the season.
The potato plants have grown flowers, so the potatoes are also nearly ready to harvest, but not quite.