Cornucopia is a horn filled with the harvest. When the horn is filled to overflowing, it represents abundance, proof of a bountiful harvest. Used as a centerpiece during the autumn, cornucopias are often woven of grapevine (grapes are harvested in the late summer/early autumn and the vine's strong and flexible which makes it suitable for weaving). Traditionally, fruit available in the autumn is used to fill the horn, but vegetables and items representing the change of the season are a lovely addition.
Here are some suggestions for filling a cornucopia...
apples
cranberries
chrysanthemums
ears of corn
grapes
maple leaves
pears
pecans and other nuts
pine cones
tangerines
winter squash and gourds