Pieces of colonial furniture, church silver, and battered duck decoys will be auctioned beginning tomorrow at Christie’s and Sotheby’s. The Americana sales are expected to bring Christie’s a total of between $15.6 million and $21.4 million at sales tomorrow and Friday. Sotheby’s auctions, which begin Friday, are estimated to fetch between $13.4 million and $25 million.

“The Americana market has gone wild,” the senior vice president and head of sales for American Furniture and Decorative Arts at Christie’s, Margot Rosenberg, said. “Last year we sold $42 million.” (Last year’s sales included a Charles Willson Peale portrait of George Washington that went for $21.3 million, swelling the bottom line.)

The highlight of the Christie’s sale is the last “Peaceable Kingdom” painting by Quaker artist Edward Hicks (1780–1849). It is estimated to sell for between $3 million and $4 million. Two other Hicks paintings are on offer at Christie’s, and Sotheby’s will offer a Hicks on Friday. “The ‘Peaceable Kingdom’ is the pinnacle of Americana,” Ms. Rosenberg said. “But collectors of Impressionist painting and even contemporary art also own his pictures.”

“Decoys are a sector that is on fire,” Ms. Rosenberg added. She said buyers for decoys are often not average collectors of Americana and folk art. “Some come from sculpture and others from hunting as a hobby.”

She said she expects two decoys — one only 9 1/4 inches high — will sell for more than $1 million combined. A red-breasted Merganser hen carved by L.T. Holmes around 1850 has an estimate between $600,000 and $800,000. It originally had been owned by Adele Earnest, a founder of the American Museum of Folk Art. A Canada goose by an unknown maker bears a $300,000–$500,000 estimate. That sticker shock price should not dismay the growing number of prominent collectors. “There are now 100 collectors who will pay $50,000 and up for a single decoy and other small objects,” Ms. Rosenberg said.

Also on offer this week is church silver, once rarely seen at auction. Since church silver was used infrequently by its original owners, the surface is usually in mint condition. “Surface matters to collectors and those pieces which have been used daily and frequently polished lose their original gray patina,” a senior vice president and the head of the Christie’s silver department, Jeanne Sloane, said. “The engraving softens and the color brightens.”

One choice piece, from the First Church of Salem, is a 1670 two-fisted beaker made by Jeremiah Dummer, the first native-born American silversmith, who worked in Boston. It bears a $150,000–$200,000 estimate. “Pieces of silver like this always break their records,” Ms. Sloane said.

Some of the furniture which could be the perfect accompaniment for that silver also boasts unusually steep estimates. Christie’s offers a Chippendale bombé mahogany desk (c. 1750), with sides that swell out in huge curves, which is estimated to sell for between $500,000 and $800,000. “In the 1950s, we sold that desk for approximately $2,000,” Albert Sack, a private Americana dealer, said. “Its value today proves the desk to be like a blue-chip stock,” Mr. Sack said.

Sotheby’s is offering the rarest piece of furniture: a Chippendale mahogany desk and bookcase dating from 1756 and attributed to the Boston cabinetmaker John Welch, who had crafted picture frames for the artist John Singleton Copley. “This is the only such elaborate piece of Americana to ever come to market,” Sotheby’s senior vice president and senior specialist of Americana, Leslie Keno, said. The desk will likely surpass its estimate of between $2,000,000 and $5,000,000. Enhancing its price is the fact that the wealthy Loyalist merchant Gilbert Deblois commissioned the desk. He paid $18 for it.

The merchant’s descendants kept the desk close to a window, so its surface is now sun-streaked. But despite that surface condition, this is no routine set of furniture. Reeded pilasters topped by carved Corinthian capitals flank its mirrored front doors, and its interior boasts a secret drawer and 27compartments for papers. Erik Gronning, also in the Americana department at Sotheby’s, called the desk “an unknown Rembrandt of Americana.” A recent discovery, this is the first time it has been offered at auction, and it has never been cited in any publication.

Despite these few blockbuster pieces, there are many more modest lots on offer. Some pieces — including ceramics and furniture such as not-so-rare chairs and tables — come from prominent institutions such as Historic Deerfield in Massachusetts, and Winterthur Museum in Delaware. “More institutions are fine-tuning their collections and weeding out duplicates,” Mr. Sack said. That means more material for bargain hunters.

So many of them may consider a New England maple dropleaf table from Deerfield dating from 1730 and tagged with only a $1,500 to $3,000 estimate to be tempting. “Prices for the middle and lower market in Americana remain soft,” Mr. Sack said. “Furniture is a good buy.”