"Mmm-hmm, yeah. They crunch on my teeth," said Teresa Widener while eating her favorite snack.

Chocolate-covered pretzels? Everyone likes those.

"I like that it has an earthy flavor," added Widener, who is 45 and lives in Bedford, Va.

French fries? Terra chips?

No, "crunch" and "earthy" aren't culinary terms of art - they're literal. Widener, a mother of two who works with special-needs children, eats rocks.

She doesn't wash them. Sometimes she just sucks off the dirt. Other times, she takes a hammer and smacks them into bite-size pieces.

It's a behavioral and/or mental-health condition called pica, the Latin word for magpie, a bird that will eat anything.

Again, the name isn't poetic hyperbole.

"People will eat anything when it comes to pica," said Dr. Jordana Mansbacher, a clinical social worker and therapist who specializes in eating disorders, including pica. "They will eat toilet paper. They will eat fabric. They will eat carpet. They will eat paper. They will eat wood. They will eat clothing. They will eat skin. They will eat metal."

Widener said rocks were an emotional crutch, but she also said she has anemia and that the rocks help treat her iron deficiency.

This phenomenon is fairly common among women, especially pregnant women, according to Mansbacher.

"Pregnant women tend to be anemic," said Mansbacher, because their nutrients go straight to the fetus. "And a lot of times they develop cravings … for ice, which is rich in zinc, and soil and clay, which is rich in iron."

But around the world and even in parts of the South, Mansbacher said, even non-pregnant women crave and eat soil because of iron deficiency. Widener is not pregnant and said she has been eating rocks for more than 20 years.

While the practice shouldn't be hidden or stigmatized, Mansbacher said, eating rocks and soil is unhealthy; it can introduce parasites, and rocks can puncture or tear internal tissue, causing bleeding.

"I suggest that a woman have a blood test to determine if there are any mineral or vitamin deficiencies," Mansbacher said via email. "If there is a deficiency, I would then ask your M.D. for a treatment plan to include vitamin or mineral supplements or an alteration in one's diet."

Watch the whole story on the full episode of "20/20."