THE PRICE of lobster usually heads dependably in one direction: up. But this time of year all kinds of surprising things happen to its price; thus restaurants have people lined up to buy two lobsters for the price of one, and some markets offer sales while others do no such thing. Even more surprises come in the eating. Most of the lobsters on the market at the moment are "new-shell" lobsters, those that have shed their shells and, like soft-shell crabs, have soft new shells that will take time to harden. These lobsters have 10 to 15 percent less meat than hard-shell lobsters, and the meat itself may be soft and watery. New-shell lobsters cost about $1 a pound less at the wholesale level than hard-shell, although the cost to the consumer may be the same because they are fragile and difficult--therefore more expensive--to handle.

According to Mel Spitz of Gloucester Lobster Co. in Landover, the meat of new-shell lobsters is younger, sweeter and better tasting than the meat of the hard-shell lobsters currently on the market. The hard-shells at this time of year, he explained, were caught at least two or three months ago and kept in pounds, where they have been fed largely on salt herring, which affects their taste. Also they may have picked up considerable moss and kelp on their shells, which adds to their weight but not to their meat. Thus, new-shell lobsters can be a good buy--at least when sold by weight rather than by size, and if the meat has firmed; a couple of weeks ago they "were terrible," said Spitz, with paper-thin shells and a small proportion of meat to shell, but they are improving each week. New-shells, he added, will gradually get firmer and the meat will fill out as they continue to develop into hard-shells. New-shells are easy enough to spot; just press the shell to see if it gives. How do you tell just-caught lobsters from those kept in pounds? Pounded lobsters tend to be darker, and may have a blue sheen around the claw. When cooked, they may appear mottled and have fuzz clinging to them, and when live they may have kelp and moss clinging to them. The dirtier they are, the closer to the bottom of the pound they have been, said Spitz, and probably the longer they have been kept.

Fresh corn and zucchini may not be in your back yard, but they are at the other end of a Metro ride now that the city has instituted a shuttle bus service from the Stadium-Armory stop to the D.C. Farmers' Market at RFK Stadium. On Tuesdays and Thursdays from 12:30 p.m. until 7:30 p.m., and on Saturdays from 9 a.m. to 3 p.m., buses will run at 15-minute intervals in August and if ridership is good will continue through Dec. 23, when the market closes for the season. While you are at the market, check out the tent where demonstrations, recipes, cooking and preserving tips, films and slides will be offered to inspire your use of the market's goods.

And if you do have zucchini in your back yard, threatening to invade you basement to attic, you may need to know about the Zucchini Cookbook, available to deal with such emergencies, for $2.75 from 212 Laurel St., Santa Cruz, CA 95060.

By now chocolate truffles are no surprise, though their familiarity does not alter their delectability. We are always delighted to be offered chocolate truffles after dinner (or, we might even confess, any time of the day). At Rive Gauche, though, we were even more charmed to find homemade chocolate caramels, dark and buttery and chewy, made in that kitchen. Chef Michel Laudier passed on the recipe, which we in turn pass along, with the warning that you will probably now crave chocolate truffles and chocolate caramels after dinner.

MICHEL LAUDIER'S CHOCOLATE CARAMELS (Makes about 100) 2 cups whipping cream 2 cups sugar 1/2 cup honey 12 ounces unsweetened chocolate 2 tablespoons butter

Bring cream, sugar, honey and chocolate to a boil, stirring constantly, for approximately 10 minutes, or until mixture reaches 256 degrees on a candy thermometer. Add butter and stir well, pour into a buttered jelly roll pan and let cool. Cut into small squares.