I had a similar experience. This picture was taken 3/2/06. I covered up my strawberry plants for the winter. When I uncovered them, I found a couple of heads of green leaf lettuce. I had grown lettuce in this bed the year before and it obviously reseeded! It was the best tasting lettuce, not bitter and it lasted for 3 family salads. I can’t seem to grow it as well when I try. J This is just one head.
Nancy in Texas