The Spink donation, which curators researched for more than three years before accepting, contains 10 paintings by American artists and 215 pieces of Asian art.

Three of the paintings are American portraits, one, an “iconic” image, according to the museum, of George Washington by Rembrandt Peale. The four Wyeths are all watercolors: pastoral portraits of trees and logs by son Jamie; subdued studies of a window and gas lamps by father Andrew, also son to famous illustrator N.C. Wyeth.

The two Rockwells are the most recognizable and valuable of the paintings. One, “Thanksgiving,” was painted for a 1943 Saturday Evening Post cover, of an Italian girl offering thanks for a meal amid the destruction of World War II, an American serviceman’s jacket draped over her shoulders. The museum estimated its worth at $500,000.

The other Rockwell, “Hot Stove League,” is a humorous portrait of two old men and a dog warming themselves by a stove and arguing about baseball, worth perhaps $1 million, according to the museum.

But it is the Asian ceramics, bronzes, glass, pottery and jade, some 5,000 years old, that will make the largest impact on the museum’s collection, officials said Tuesday.