The White House has acquired a rare painting by George Caleb Binham (1811-1879), "Lighter Relieving a Steamboat Aground." The painting is valued at $500,000. The White House had tried to buy another Bingham recently at auction, but was outbid at $850,000.

The Bingham painting and a new painting on loan, "Washington Crossing the Delaware" by Eastman Johnson (1824-1906), after one by Emanuel Leutze, are considered two of the most important American paintings ever to hang in the White House, according to Clement Conger, the curator. Richard Manoogian is the lender.

Rosalynn Carter announced the gifts at a meeting yesterday of the White House, held in the State Dining Room.

A gilded beech sofa, originally made for the Blue Room by Pierre Antoine Bellange in Paris in 1817, has been given to the White House by the Edison Institute. The sofa is considered a remarkable find because it was bought for the White House by President James Monroe, after the fire of 1914. Monroe wanted a French mahogany suite, but the purchasers asserted that "mahogany is not generally admitted in the furniture of a salon, even at private gentlemen's houses," and sent gilded pieces instead.

Mrs. Carter also showed the committee the East Room fireplace mantels and baseboards which have been marblized in white and gold. The mantels are marble, but of a deep red color of which Conger and his architectural adviser, Edward Vason Jones, don't approve.

Among the other important acquisitions announced yesterday was the portrait of Benjamin Latrobe by Charles Willson Peale. The $125,000 portrait shows Latrobe, the second architect of the White House, with his eyeglasses pushed to the top of his head. It hangs now in the Cross Hall on the State Floor.

An old gift to the White House, a jeweled Tabriz prayer rug, has been repaired and will be rehung. It was a gift to Theodore Roosevelt from a Persian diplomat. It is adorned with 44 emeralds, five amethysts, 26 turquoises and 16,000 seed pearls. CAPTION: Picture, Rosalynn Carter and Richard Manoogian with "Washington Crossing the Delaware"; by Harry Naltchayan-The Washington Post