Story where real food is illegal but there is an underground org to rebuild

Question

I can’t remember the title/author of a short story or novel in which real food is scarce and illegal to have. The main character secretly grows vegetables and raises rabbits for meat. There is something about obtaining Quicksilver which is key to him connecting with a secret organization that wants to start the world over and recruits talented people like him (because he has farming skills). I recall a passage where he is having a meal with another person eating govt approved food, and she is described as obediently chewing down the rubbery morsels, or something close to that.

I most likely read this in the late seventies. It might have been in a book of Sci Fi short stories or a short novel either laying around my house (lots of older siblings with books) or in a teacher's unofficial lending library. I have no recollection of any cover/art. Things I can recall about the story: The main character is an adult but young; I think he learned his love of food and skills raising it from family that is no longer alive; he meets a young woman who becomes a possible love interest - that is whom he is with when he eats the govt food. When he decides it is safe, he feeds her a real meal at his home and she bursts into tears at the pure novelty and enjoyment of the flavor and texture of real food. Also going on is the sense that he is being watched/followed and is worried about getting caught and prosecuted for his food habits. In the end it turns out the people watching him are the resistance who are planning to move to a new place (?sketchy memory here!) where a civilization can start anew without the current regime's restrictions. They have limited capacity so are choosing candidates carefully. The main character does come to the attention of authorities, and is in danger of being found out and stopped before he is claimed and rescued by the new organization. I can't remember any details about the revelation and the transport, other than a vivid scene where he is in something resembling an elevator where something very strange happens. Other people in the vehicle that are not in possession of the quicksilver thing and not chosen by the resistance do not survive the experience. There is a detailed description of how the light changes and how it affects the appearance of other people in the "room", especially a woman antagonist on board with him. Something about the outline of the makeup on her eyes becomes illuminated. The story ends on a note of potential hope. The main character did not seek out the resistance, is somewhat wary and skeptical about its existence and the feasibility of its mission, and eventually follows their instructions to join them only when it becomes clear that he is about to be nabbed by the authorities.

Answer 1

If I have a purpose in life, it's to answer story identification questions where the questioner has remembered most of the salient points of Frank Bonham's The Missing Person's League, first published in 1976 (and previously asked and answered here):

• The food shortages, environmental degradation, and protagonist's secret, underground garden/rabbit pens

The protagonist and his father dug out a secret basement, hiding the dirt in the walls and covering the trap door with the refrigerator, where they grow their own food. The cover story is that they're actually foraging illegally.

• The use of quicksilver/mercury as the key to a puzzle

Poured into a door mechanism to open a mercury lock

• The elevator that kills occupants

is a booby trap in the anteroom to a secret facility; it kills intruders unless they're wearing special rings only given to desired, invited individuals

• The "resistance" is a group that finds people who will be useful

after the environment collapses, most of humanity dies, and the selected survivors emerge from suspended animation to begin anew