Quark's Treasure was a Ferengi shuttle that belonged to Quark. The shuttle, which was capable of warp speed, was given to Quark by his cousin Gaila to repay him in part for loaning him the latinum to start a business.
Shortly after receiving the shuttle, Quark took Rom and Nog to Earth so that Nog could begin attending classes at Starfleet Academy. He also intended to take a side trip to Orion to sell a load of kemocite that he had found on his ship. Odo had snuck on board the shuttle and used his shapeshifting abilities to hide on the shuttle - intending to capture Quark in the act of kemocite smuggling.
When they reached Earth it was realized that Gaila had sabotaged the shuttle's warp drive so that the drive could not be shut down, nor could the warp core be ejected. Rom forced the ship out of warp by exposing the kemocite in the shuttle to warp plasma, which was successful. However it threw them into a time warp which sent them back to 1947, and they crashed near Roswell, New Mexico. The Ferengi were taken into custody by the United States Army, and Quark's Treasure was subjected to detailed examinations. After escaping custody, Rom was able to use the remainder of the kemocite to recreate the accident, and bring them back to the 24th century.
Afterwards, Quark's Treasure had to be sold for salvage as she was a total loss. With the proceeds, Quark, Rom, and Odo were able to buy passage back to Deep Space 9. (DS9 episode: "Little Green Men")
In the years following the crash of Quark's Treasure in the desert, a top secret research program was undertaken to decipher the technology found on the ship. This in part led to the development of space vessels such as the DY-100. (TOS novel: The Rise and Fall of Khan Noonien Singh, Volume 1)
The incident also spurred a secret organisation that defended Earth against alien threats into existence, and centuries later the organisation still had copies of schematics of the shuttle from the incident in their possession. (TNG comic: "An Inconvenient Truth")