Those "new" pieces, though, are usually rusted scrap metal he found at the recycle yard or stone pieces he's hauled back from his grandfather's old farm in Green's Ferry to his family's home on Hope Street in Jackson.
"Everything I have kind of has meaning," Friedrich said as he stood in his driveway next to a fire hydrant hidden in native Missouri plants.
The light pole that shines on a water fountain in his side yard came from St. Louis. His father, a union electrician who drove to and from St. Louis every day, bought the pole and kept it in the basement.
"When he passed away, my brothers gave it to me," Friedrich said. He had it sandblasted and then he painted each section a different color and erected it in the yard.
Nothing surprises his wife anymore.
"One day he came home with a whole truckload" of ire hydrants, said Lisa Friedrich, who admitted she loves gardening as well. "He was only allowed to keep two."
The couple moved into the house in 1996 and the yard and objects have changed and grown each year.
Caladiums and impatiens flow out of old sewer pipes like a leafy flood. The Friedriches estimate they have about 20 feet of old sewer pipes stuck in the garden. Rusted water meter covers make a path around the fishpond so 6-year-old Tate Friedrich can watch and feed the goldfish.
"That's my favorite part right there," Friedrich said, pointing to the small form in the floor at the entrance to the garage.
He has sculpted some heads that sit around the yard like warped guests at a garden tea party. One, shaped like the comic book villain the Joker, covers the chimney to the fire pit.
"Smoke will come out of his ears and then fire comes out of his mouth," he said.
His yard serves partly as storage for things he thinks he might use someday in something. He kept an old chain for more than four years before he figured out what to do with it.
Friedrich's mother had cancer that spread to her spine. She had surgery and got metal rods put in her spine. After that, Friedrich decided to use the metal chain as the spine in a wood sculpture.
A few years ago he was mowing a neighbor's yard and found flat stones buried there. She told him he could have them if he could dig them up. The pieces, which he said stuck out of the ground just a few inches, turned out to be the blocks used to build the old Jackson courthouse. Some were two feet in the ground. Now they're stairs and parts of walls and holding up an old porcelain sink.
"I hide them everywhere," he said.
Friedrich won't throw anything away.
"I'm always thinking some day something will come out of it."
Go to semissourian.com to see more photos from Rob Friedrich's garden.