This is a story about pennies.

The average American household has some $90 worth of pennies stashed in jars, languishing underneath sofa cushions and lost beneath car seats.

Every day, the U.S. Mint makes about 30 million more of them, and on Tuesday, a small number of those coins caused me to consider their value.

While standing in a checkout line at the grocery store, a woman behind me reached down to the floor, picked up a coin and placed it on the conveyor belt.

“This is yours,” she said, pointing to the coin. “You dropped it.”

It was a penny. I had been digging through my purse, reaching for dollar bills, when it must’ve fallen to the floor.

“Thank you,” I said, smiling.

“You’re welcome,” she replied, smiling back.

I put the penny in my purse. It joined a collection of coins that swims around in the bottom of my leather shoulder bag.

How nice, I thought, that someone would bother to reach down to pick up a penny, especially since it wasn’t hers in the first place.

At lunchtime, at my favorite meat ‘n’ three restaurant, I reached into that pond of coins at the bottom of my purse for four quarters. I always tip the waitress there at least $1, and I was out of bills.

She, the waitress, is building her first house. She can bus a table like nobody’s business. And every day, the plastic cup she keeps near the cash register fills up with tips she earns with her smile, her good jokes and her sincere interest in who you are and how you’re doing.

So, at lunch’s end, I went fishing in the purse pond and came up with a collection of coins that included several quarters, dimes, nickels and a handful of pennies — amounting to at least a dollar, maybe more.

“Here,” I said, not wanting to offend by a tip that included pennies, “do you mind if I just give you all this?”

“Heck no,” she said, “I’ll take everything I can get.”

Then, while at an arts supply store, I noticed a tall, clear jar with the story of two Hart County high schoolers — siblings — who are hoping to raise enough money to go with the school’s band on a trip to London. The jar was approximately one-fourth full of mostly change, included a slew of pennies. A note on the outside of the jar estimated that the trip would cost each student 20 pennies per mile.

“Real good kids,” said the lady who was helping me frame some pictures. “Their grandmother and great grandmother live with them, and they do a lot to take care of them.”

Pennies. A few hide underneath sofa cushions. Some swim in the bottom of pocketbooks. Many more build dreams — houses and trips from small towns to sophisticated cities.

And even just one, picked up from the grocery-store floor, offers special compensation — a smile exchanged between strangers.

Salley M. McInerney can be reached by e-mailing salley@hartcom.net.