Gardner Minshew of the Jacksonville Jaguars has always been careful with his cash. The 23-year-old rookie quarterback "is known for not spending any money," his mother, Kim, told the Wall Street Journal.

He still drives the used Acura she got him when he graduated high school, she added.

Anecdotes from Minshew's college days confirm his mother's story: After one of the biggest games of his college career — the 2018 Alamo Bowl, when he led Washington State to a win over Iowa State — Minshew, like all college players competing in the prestigious bowl games, received a $700 travel stipend to get home for the holiday break.

Rather than spending it on a flight home to Brandon, Mississippi, "Minshew got thrifty, pocketing the money and hitching a ride with a few Brandon-bound buddies who'd made the trip to San Antonio to watch him play," the Spokesman-Review reported this year.

Even after he was selected by the Jacksonville Jaguars in the 2019 NFL draft, which came with a $190,884 signing bonus, Minshew chose to play it safe and didn't sign a lease right away. "He would not get an apartment until he saw his name on the roster," his mother said.

In the NFL, just because you're drafted doesn't guarantee you'll make the 53-player roster. As SB Nation explains, "not all draft picks are created equal." And players selected in the sixth round, like Minshew was, "must fight each day to make the roster out of camp."

He has earned his spot since draft weekend: After Jaguars starting quarterback Nick Foles fractured his clavicle in the season opener, Minshew stepped in. He's played in the last five games and hasn't disappointed, already earning Rookie of the Week four times and Rookie of the Month for September.

Minshew, who will earn a base salary of $495,000 in 2019, eventually got an apartment. And it's outfitted with the essentials — things like pots and pans — thanks to his mom: "I knew if I didn't send him things for his apartment, he wouldn't have them."

Don't miss: $100 is worth about $86 in New York—here's what it will buy you in every US state

Like this story? Subscribe to CNBC Make It on YouTube!