In the United States, the last Monday in May is Memorial Day, a holiday that honors people who died in military service during wartime.
The end of May also marks the beginning of a less serious kind of war. It is one many living Americans fight each summer. It is a battle for - and about - the perfect lawn. That's right, the lawn: the grass around most American houses.
Virginia Scott Jenkins is an expert on Americans' extreme interest in lawns. In fact, in her book on the issue, she calls it an "obsession."
She says that, in the minds of many Americans, the perfect lawn looks like a soft, green carpet. "One height, one color, one type of grass, one consistency."
Many Americans believe such a lawn does more than make a house or neighborhood look good.
"An orderly front lawn is supposed to be representative of an orderly household," Jenkins says. "Good neighbors have good front lawns, good citizens have good front lawn(s)."
Lawns are so linked to American identity that they are part of some U.S. government buildings overseas. Architectural historian Jane Loeffler notes that the design for the American embassy in Berlin, Germany, for example, includes an outdoor area made to look like "the beloved American lawn."
Man against nature
Lawns are not only a big deal for Americans - they are also big business.
The Bloomberg news service found that Americans spend about $40 billion every year on lawn care. They pay for lawn mowers to cut the grass and chemical fertilizers to make it grow. Many also pay other people to help keep their lawns thick and green.
These things are all weapons in a war against natural forces that, in time, may make lawns look wild or brown. So why do so many Americans fight such a war each summer?
"People have grown up believing that that 's what [a lawn] is supposed to look like," Jenkins says. "Because of tremendous advertising campaigns and pressure from the lawn care industry, which is a multi-million dollar business."
Jenkins says that lawns also show a person's social position. "Do you know how much money it takes, and time and effort, to grow a perfect front lawn?"
A major reason why lawns are so much work is because they are completely man-made, she adds. "There is not anything natural about them."
Even the grass seed historically comes from Europe and Africa.
Man against neighbor
Of course, not everyone accepts traditional American lawn culture.
In recent years, another front on the lawn war has formed. It is between people who want to control their lawns, and those who want to let native plants grow naturally.
In 2014, in an area of Virginia about 80 kilometers outside Washington, D.C, a couple entered into a legal fight with their neighborhood about their lawn. The couple's house is on about 2.2 hectares of land. They cut and care for the grass on part of that land, but they permit the rest to grow naturally into a meadow, with tall grass and wildflowers.
The couple, Michael and Sian Pugh, told the Washington Post newspaper that they enjoy watching the butterflies, birds and deer that visit the meadow.
But the Pughs are part of a homeowners association - a group that cares for and governs a neighborhood. The homeowners association, or HOA, makes and enforces rules about that area. One rule that is common among HOAs across the country is that members must keep their grass short and green. The Pugh's HOA says their meadow violates this rule and is not fair to their neighbors.
One concern is that the meadow might reduce the value of other people's homes in the area. People who sell property say a well-kept lawn is an important part of making a house attractive to buyers.
Another concern is that the neighborhood will no longer feel pleasant - or even safe - to the people who already live there.
But the Pughs and their supporters say meadows such as theirs add value because they are better for the environment. The native grasses have deep roots and can protect against flooding. And the wildflowers invite bees and butterflies, which help crops and other plants grow.
Alternatives to the traditional American lawn
Activists in other places have made similar environmental arguments.
They say the chemicals that "feed and weed" traditional lawns can hurt people and animals. They criticize the water waste involved in keeping lawns green, especially in places that face drought.
They also note that some kinds of lawn mowers use gas and pollute the air. And they say that, in general, keeping lawns under control takes too much time, and is a job that few homeowners really want to do.
In answer to these arguments, some people have found other ways to use the area around their houses. They use plants that grow easily. Or they put in vegetable gardens and fruit trees. Or, like the Pughs, they permit nature to take over and hope their neighbors w ill come to accept a new definition of "lawn."
By the way, the Pugh's case was never fully resolved. The HOA decided not to go to court. But HOA officials are also re-writing the rules so that no one else tries to grow a tall, wild meadow in a place where neighbors prefer a short, orderly lawn.