Every year about this time, truckloads of fresh white corn, vine-ripened tomatoes and mouth-watering watermelons start making their way to dozens of certified farmers' markets and roadside stands throughout California. The new "Farmer-to-Consumer Directory," just published by the UC Davis-based UC Small Farm Center, will help make treks to these local gardens of good eating a little easier. For people who want to harvest their own bounty, the directory also lists pick-your-own operations. Many of the growers -more-listed in the directory have picnic areas, nature trails, fishing ponds or food festivals. Directory listings are organized by region and include information about location, season, operating hours and available products. The directory lists 21 farm trail organizations that publish maps to local farms. To obtain a copy of the directory or to learn more about California's small farmers, contact the Small Farm Center at (916) 757-8579. Tip by John Stumbos, Agricultural Communications, 757-8934.