Lammas (or Lughnasadh) occurs in late July and early August. It marks the beginning of the harvest. It's the first of three harvest festivals and is usually associated with ripening grain. It heralds the coming of Autumn.
"My long two-pointed ladder's sticking through a tree Toward heaven still, and there's a barrel that I didn't fill Beside it, and there may be two or three Apples I didn't pick upon some bough." - for "After Apple-Picking" (photographer unknown)