The Cornucopia symbolizes abundance, usually seen as a curved goat's horn, filled to overflowing with fruit and grain but which could be filled with whatever the owner wished.
The Cornucopia has always been associated with ThanksGiving and has been a symbol long before ThanksGiving as we know it today. Man has always been thankful for the abundance provided by nature or God.
The Cornucopia or horn of plenty originally came from ancient Greeks mythology and carried on until today with a similar meaning.

      The oldest account of the origin of the Cornucopia. Zeus (Jupiter) was committed by his mother Rhea to the care of the daughters of Melisseus, a Cretan king.
They fed the infant deity with the milk of the goat. Jupiter broke off one of the horns of the goat and gave it to his nurses, and endowed it with the wonderful power of becoming filled with whatever the possessor might wish.

      The horn of plenty was regarded as the symbol of inexhaustible riches and plenty and became the attribute of several immortals and of rivers as fertilizers of the land.

      An other story is about the fifth labor of Hercules. In which Augean Stables- cleaned in 1 day by diverting a river. Hercules fought the river-god Achelous, while they were delayed on their journey by the overflow of his waters.
Hercules fought the river-god Achelous who could take the form of either a snake or bull. Achelous failed to defeat Hercules as a snake ad took the form of a bull. Hercules ripped his horn off and diverted the river.
This land was very fertile, and this is meant by the horn of plenty. Than the Naiads took the horn, consecrated it, and filled it with fragrant flowers. (in the Roman version it was the goddess, Abundantia) adopted the horn and made it her own, and called it "Cornucopia".

      Abundantia was the Roman goddess of abundance, prosperity and good fortune. The cornucopia ("horn of plenty") was used by Abundantia to distributes grain and money.

      After the Roman occupation of France, Abundantia remained in French folklore as Lady Hobunde.