I'm not a Wiccan or Pagan, but I can answer this if you like. The answer depends on the time of year, and what you're trying to accomplish. At the spring equinox, which just happened, usually eggs are offered as a sign of returning life. (This is where the Christian Easter egg custom comes from). Spring flowers are appropriate too, for the spring equinox and for Beltane (usually celebrated around May 1). A lot of families go heavy on the roses at Beltane. Midsummer, the summer solstice, is a fire festival, so you'll encounter bonfires or candles. People often stay up all night celebrating on this, the shortest night of the year. Some Christians observe some of these customs as "St. John's Night." At Lughnasa in August, the harvest festival sometimes called "First Fruits," you offer exactly that: the first or near-first harvests of the year (even if you're a city dweller and have to buy something fresh at the store). The flowers usually associated with this are sunflowers. A lot of people will home-bake bread to symbolize the grain harvest coming in. At the October festival of Samhain, you'll usually see gourds and pumpkins and straw dolls (which represented the dolls made from stalks of edible grains, like oats, in the old days). This festival is about things passing away and cold days coming. Pumpkins and similar easily-stored foods represented staying alive in the winter in the days before a world market for food and preservation by refrigeration, etc. At the winter solstice, the other fire festival, fires are usually lit to represent the return of the sun, and evergreens (as a sign that life is present even in the dark of the year) are traditional offerings. It may be a tiny fire, just a single candle. For smaller holidays, or for personal prayer, it's up to you. Most people don't have any trouble figuring out what best represents their intentions; Wicca and Paganism aren't as specific about these things as, for example, Leviticus in the Judeo-Christian scriptures.