The two most common labors for July depicted in the calendar images of Books of Hours (and in psalters and prayerbooks like W.425), are mowing hay, and harvesting wheat with a scythe. This image from f. 7r of Walters Museum prayer book fragment W.425 shows a fairly typical scene of two men in a field reaping the wheat with scythes. The margin shows a medallion featuring a lion, the zodiac sign for Leo. I have no idea why there appears to be grid; the lines don’t appear thick enough to be stacks of mown hay.
This is another month with flowers in the border, and again, they are close to realistic in style.