As a child, Meghan Swann had suffered several bouts of strep throat, and when she was a teenager, she thought she felt another one coming on. The main symptom was familiar  a dull sore-throat pain.

But this time something was different; there seemed to be a foreign object stuck in the back of her throat, something she couldn’t quite swallow. “So I pushed on my tonsil, and something popped out,” Ms. Swann said. The yellowish object was about the size of a piece of gravel and had the sulfurous odor of bad breath. “I thought it was a piece of food or something,” she said.

From then on, Ms. Swann, now 25 and living in the St. Louis area, engaged in a secret ritual: popping the mushrooming bits of debris out of her tonsils with a cotton swab whenever they got big enough to cause discomfort.

One day, she mentioned her problem to her mother  and was surprised at the knowing response. Those squishy little things were tonsil stones, her mother explained, and she sometimes got them too. This year, when Ms. Swann posted a blog entry about her stones, readers came out of the woodwork to tell her they also had the problem. “Wow,” she remembers thinking, “there’s a lot of people out there with this.”