Every spring my lawn includes a 10 square foot patch of grass that is much taller and greener than the rest of the lawn. Although not at a low point, this patch is also much more full of moisture than the rest of the lawn. The taller grass is almost perfectly tubular, resembling green thin spaghetti. First mowing is difficult because of the moisture, but by the second mowing all obvious evidence of this condition is gone. Any ideas?