There is much speculation on who actually started Memorial day or Decoration Day. However, it officially started on May 5th, 1868 by General John Logan to honor the dead after the Civil War.
It is claimed that African Americans founded Decoration Day at
the graveyard of 257 Union soldiers labeled "Martyrs of the Race
Course," May 1, 1865, Charleston, South Carolina.
At nine o'clock in the morning on May 1, the procession to this special cemetery
began as three thousand black schoolchildren (newly enrolled in freed
men's schools) marched around the Race Course, each with an armload of
roses and singing "John Brown's Body." The children were followed by
three hundred black women representing the Patriotic Association, a
group organized to distribute clothing and other goods among the freed
people. The women carried baskets of flowers, wreaths, and crosses to
the burial ground.
The Mutual Aid
Society, a benevolent association of black men, next marched in cadence
around the track and into the cemetery, followed by large crowds of
white and black citizens. The "First Decoration Day," as this event
came to be recognized in some circles in the North, involved an
estimated ten thousand people, most of them black former slaves. During
April, twenty-eight black men from one of the local churches built a
suitable enclosure for the burial ground at the Race Course. In some ten
days, they constructed a fence ten feet high, enclosing the burial
ground, and landscaped the graves into neat rows. The wooden fence was
whitewashed and an archway was built over the gate to the enclosure. On
the arch, painted in black letters, the workmen inscribed "Martyrs of
the Race Course"
their spring blossoms on the graves in a scene recorded by a newspaper
correspondent: "when all had left, the holy mounds — the tops, the
sides, and the spaces between them — were one mass of flowers, not a
speck of earth could be seen; and as the breeze wafted the sweet
perfumes from them, outside and beyond ... there were few eyes among
those who knew the meaning of the ceremony that were not dim with tears
of joy." While the adults marched around the graves, the children were
gathered in a nearby grove, where they sang "America," "We'll Rally
Around the Flag," and "The Star-Spangled Banner."
dedication ceremony was conducted by the ministers of all the black
churches in Charleston. With prayer, the reading of biblical passages,
and the singing of spirituals, black Charlestonians gave birth to an
American tradition. In so doing, they declared the meaning of the war in
the most public way possible — by their labor, their words, their
songs, and their solemn parade of roses, lilacs, and marching feet on
the old planters' Race Course. After the
dedication, the crowds gathered at the Race Course grandstand to hear
some thirty speeches by Union officers, local black ministers, and
abolitionist missionaries. Picnics ensued around the grounds, and in the
afternoon, a full brigade of Union infantry, including African American Troops,
marched in double column around the martyrs' graves and held a drill on
the infield of the Race Course.
Other cities lay claim to the founding also and you can read more, if you're interested here No one is sure if this ceremony influenced General Logan but only 3 years later, Memorial Day came into national attention.