On the morning of June 4, Bev Thoms sent her son to the bottom lands of their 60-acre farm in Dickerson where the fields are glorious with the purple of wildflowers.

Thoms took the flowers he picked to Rockville and placed them on the dais of the Montgomery County Council. "They are to remind you of the beauty of Dickerson," Thoms, a member of the Sugarloaf Citizens Association, told council members on that opening day of work sessions to decide if a $170 million trash incinerator should be built in the rural woods of Dickerson or at the county's center in Shady Grove.

The gesture, Thoms later explained, sprang from her rage at Montgomery County's apparent intention to place the "mass burn" facility near the farm she and her husband started in 1974, a farm that is as much a way of life as a place to raise their four children. The flowers, she said, were her way of trying to show she had some control over the situation.

Watching the council with equal interest that day was Peggy Erickson, president of the Concerned Citizens and Scientists for a Healthful Environment, a group whose members oppose placing the incinerator at an alternate site in Shady Grove. Erickson empathized with Thoms. Both women have placed much of their lives on hold so they can fight county plans to build the mass burner. Both believe the incinerator is environmentally dangerous and that the solution to the trash problem lies in recycling.

But when the seven-member council meets today in an attempt to make a final decision, Thoms and Erickson will be about 18 miles apart on the issue -- the distance between Dickerson and Shady Grove.

"Unfortunately it is us or them," said Erickson, who lives in Washington Grove.

After months of lobbying, leafleting, studying technical materials, conducting night meetings and trying to rally public support, one of the citizens groups will have swayed the county government. For the other group, the decision will be just the beginning of a promised court battle to stop the incinerator.

In a nonbinding straw vote June 25, the council had voted 4 to 2 to build in Dickerson. But lobbying continued over the holiday weekend, as telegrams and phone calls poured into the council offices yesterday.

For the people from Dickerson, the goal is to persuade at least one council member -- Michael L. Gudis and Isiah Leggett emerged as the latest targets -- to change his vote. Shady Grove residents, who defeated a 1982 incinerator plan in an impressive show of citizen clout, were twisting arms to fight off a last-minute switch.

Dickerson, with a population of about 10,000, appears politically outnumbered by Shady Grove, which has about 200,000 nearby residents in Rockville and Gaithersburg. "We just don't have the votes," said Thoms.

Sugarloaf Citizens Association, born in 1973 of an attempt to place another unwanted facility, a wastewater treatment plant, in the county's far western reaches, believes it has logic and cost on its side. Estimates by council staff show that the cost of building the facility at Dickerson would be nearly double that of building it at Shady Grove, where a garbage transfer site is located. Much of the added cost involves rail transportation to haul garbage 18 miles from Shady Grove to Dickerson and a return trip for the resulting ash.

"Can you believe anything so absolutely, positively ridiculous? . . . Here they are cutting money from the schools but they have millions to throw away to gallivant your garbage all over the county," thundered Barnesville Mayor Elizabeth H. Tolbert. "Ants, we are just ants to them."

That's at the heart of why Dickerson was chosen for the incinerator, said Sugarloaf Citizens Association President Lynn Lipp. "We are a nonenitity to county government," Lipp said. " . . . in terms of county services, in terms of input, the county line might as well end at Rte. 118."

Joining Tolbert for an interview in the antique-filled den of her family home, Thoms and Lipp tick off other county ideas for their area: a waste-water plant (defeated by citizen opposition); a landfill (also defeated); a site for sludge burial (stopped after about two years) and a leaf composting plant (now in operation). The incinerator, though, is the most serious threat, Tolbert said.

"Can you imagine" proposing all these facilities for Silver Spring or Bethesda? Thoms asked. "Can you imagine them treating the people of Shady Grove that way?"

It is one of the few suggestions of bitterness toward Shady Grove. Each organization is reluctant to criticize the other. It is not, they say, a case of citizen versus citizen. And the groups understand each other -- the constant interruption of the telephone as information is exchanged and assignments handed out; the frustration as families and jobs are slighted to attend government meetings or to go to the library for research.

Thoms, a nurse with a master's degree in community health, doesn't have time now for the private consulting that supplemented her family income. Erickson, trying to get started in selling antique linens, confesses she feels guilty if she takes a day off to go to the movies with her son. Lipp, like Erickson, admits to still feeling queasy about speaking in public.

Concerned Citizens, although newer than the Sugarloaf group, has been fighting the incinerator longer. Its 1982 defeat of an incinerator eventually led to the alternate selection of Dickerson. Erickson said she can empathize with the Dickerson group but she wouldn't undo anything.

If the mass burn facility must be built, Erickson said, it should be placed where fewer people would suffer from what she claims are adverse health effects. Economically, she agrees, Dickerson presents some additional operational costs, but she argued that there are economic costs involved "in taking some of the most valuable land in the county {at Shady Grove} and making it a garbage dump."

To that, Thoms drove to a quiet green meadow and with a sweep of her hand pointed out one of the possible sites for the plant. "That's compatible land use" for an incinerator, she said, quickly apologizing for her sarcasm.

"We're not just fighting against something, we are fighting for something," she said, and then related the plot of a film that was produced for the Sugarloaf group. Titled "A Fatal Beauty," the film talks about the breathtaking beauty of the Sugarloaf region, a beauty that attracts people, which increases development, which, in turn, destroys the beauty. "That's the point," she said.

CAPTION: Bev Thoms and Lynn Lipp stand before a proposed Dickerson site for a Montgomery County garbage incenerator.