The cars were waved onto the rolling lawn of a little yellow farmhouse owned by a member of the hunt club. It was one of the stops on the annual Potomac Country House Tour. With the festive air of trick-or-treaters, the visitors lined up at the door.

In the parlor, two grinning foxheads flanked the fireplace. Photos of the hunt hung in rows, and nailed above the door were foxtail trophies.

In the next room, there was another sort of trophy. The guide was describing the grand piano, but all eyes fell on the huge bronze lion stretched beneath it. This, she explained, "was purchased at an auction" -- she thought for a moment and added -- "after a cocktail party."

House tours, and the fall is the time for them, offer elegance with a touch of eccentricity. People open their homes and show how they live -- which makes going on a house tour a voyeur's delight. Some of the homes are historic; othes are notable for their exciting architecture or interior design. Some, like this one, are just kind of fun.

Like cocktail-party guests, the company trekked from room to room exploring and picking up gossipy tidbits: in one room that the owner had grown children; in another that he was "a bachelor for many years." Walls were covered with photos of him and a beautiful woman, "his bride of 18 months," we were told. Other volunteers began pointing out the changes the wife had made in "what he called his bachelor pad." She apparently had overlooked a slogan tacked up on the kitchen wall and almost concealed by a broom handle. But we found it: "Tuesday night is poultry night. Every lady gets a free goose."

We saw elegance in other homes, selected by committee at the St. Francis Episcopal Church, which sponsors the event. Very often the participants aren't chuch members, says June Whelan, parish secretary, but "just people in the community" who open their houses as a service to the church and its school for handicapped children. On the house selection committee, there's always someone who has been in Potomac for a long time, who knows the local homes inside and out. "You can't just drive by and see an ostentatious house and choose it without seeing the inside," she says. "Sometimes it's the smaller, less pretentious house that is more interestingly decorated."

From the farmhouse we drove on to a recent, custom-built home and entered through an enormous central hall done in salmon marble chosen by the wife. Here, the library looked like -- a library, with a railed wooden walkway past the shelves. One room was dominated by an oil depicting a favorite section of the Pacific that the wife had commissioned an artist to paint. We lingered in the labyrinthine master bedroom suite, to hear the guide as she gestured toward a pair of brandy snifters telling group after group that this is where the wife and her husband, a business executive, drink brandy in front of the fireplace. A typed card on a bedside table indicated that the lady of the house "skis, plays tennis and cooks."

A colonial house on the circuit -- a short, pleasant drive on an early-fall day -- held a railroadiana collection. Yet another was notable for its emphasis on ways to get wet -- a pond, a swimming pool and a sunken bathtub under a skylight -- not to mention certain little amenities such as an efficient closet for men's ties, a tennis court and a chamber of Chippendale and the like, overlooked by a balcony outside a guestroom.

After the tour was over, the postscript was sweet: we drove to the church for tea, where we nibbled many sugary dainties and scones with Devonshire cream. they want to make it through the afternoon, and remember to keep your cancelled check when admission is tax-deductible.

THIS FRIDAY, SATURDAY & SUNDAY -- It's the Waterford weekend, the 38th year for their homes tour and crafts exhibit, daily from 10 to 5. Built over 150 years ago, 10 privately owned homes will be open to visitors. Weaving, leatherworking, pewter-casting and candle-making will be demonstrated in the town. There are shops to visit, things to buy -- fresh apple butter, open-pit barbecue, dried flowers, handcrafts -- and a sitdown lunch for $3.95 (chilredn pay $1.75) at the elementary school. Admission is $5; free for children 12 and under. Take Route 7 through Leesburge to Route 9, then this to Route 662 into Waterford. For details call 703/882-3018.

SATURDAY -- Don't Tear It Down is sponsoring its "First Annual Architects Tour," from 11 to 4. A tour of 16 offices, it's a chance to meet some of the city's most prominent architects and see where they work. Lewis & Holt, for example, occupies the 1912 Louise Hand Laundry. And Arthur Cotton Moore's office is in a recycled Georgetown garage. If you take the tour, you can attend a reception held at the International Institute of Interior Design, 2225 R Street NW, from 3 to 5. Tickets will be available for $9 on tour day at 1056 Thomas Jefferson Street NW and 1320 19th Street NW. Phone: 737-1519.

SUNDAY THROUGH NOVEMBER 1 -- The ninth annual Decorators' Show House is the most concentrated tour going and an opportunity to develop your critical eye. In Strathmore Hall, a hilltop mansion owned by Montgomery County at 10701 Rockville Pike, 28 designers have refurbished -- temporarily -- the colonial revival residence designed by Appleton P. Clark Jr. and built at the turn of the century as a summer house for Captain James Oyster. On view will be 39 rooms decorated with great ideas: a drawing room in creamy silks and suedes, a boy's bedroom in a nautical motif. Even Pepco has gotten into the act with quilted window treatments, ceiling fans and other energy-savers. When the senses begin to reel, there's a tea room and an art gallery, along with antiques and boutiques. Admission is $6; no children under 8 admitted. It all goes to the National Symphony Orchestra. Hours: Monday, Tuesday, Thursday and Friday, 10 to 3; Wednesday 10 to 3 and 6 to 8;