The show is currently airing its eighth and final season.
Allison Janney didn't leave the set of Mom empty handed. The 61-year-old actress appeared on Wednesday's episode of The Tonight Show Starring Jimmy Fallon, and revealed what items she took from set before the series wrapped.
The first item was important to Janney, as it's something her character, Bonnie, sported from day one -- even if no one realized as much.
"No one knew I was wearing a wig. And I come in for this season of Mom and the producers see me like this [with grey hair], and they're like, 'What have you done?! You should've asked us before you did this to your hair!'" Janney recalled. "And I'm like, 'Guys, I've been wearing a wig since season one, but nobody knew it.' Everyone in the world knows it now. But that wig is coming with me."
Janney also swiped "a few pairs of sweatpants," noting, "my character Bonnie loved to be comfortable, as does Allison Janney, so I took a lot of sweatpants and made off with them."
The CBS series is currently airing its eighth and final season. Anna Faris, who starred as Janney's daughter on the series for seven seasons, announced her departure last December. While Janney opted to return, the show was canceled in February.
Janney said the show's conclusion is incredibly bittersweet.
"It's everything, as everything is. It's never one thing," she said. "Sometimes I'd be driving on the lot and be like, 'Oh my God. This is the lost Monday I'll be driving on the Warner Bros. lot.' And I was filming myself and of course that one day was a guard who didn't know me, so it was like, 'Can I see your ID?' And I was like, 'It's me!' He didn't know who I was."
On the set of the final season, Janney said, sometimes "everything" would make her cry, while other times she'd feel "so excited" for a "new chapter of life."
"It was the biggest emotional rollercoaster ride," she admitted. "Sometimes people would be sobbing and I'd feel nothing. I'd be like, 'What's wrong with me? What's wrong with me?' Literally everyone was all over the place. It was really sad. It was such a family we had here."
In addition to being personally bummed over leaving her Mom family, Janney is "sad" that the "important" stories the series told are ending.
"I think it's so great when you get to entertain people, but also put something out there in the world that helps destigmatize something like recovery and make it more approachable to people," she said, alluding to her and Faris' characters' struggle with addiction on the show. "It's done so much for so many people. I get tons of letters and fans coming up to me, [who are] so appreciative of what the show's done for them."
Now that Mom is wrapping up, Janney is looking ahead and excited to doing "something completely different" for her next project, Lou.
"I'm going to go do an action-thriller movie. I'm about to start training with a fight trainer two hours a day and learn to fight to kill and be a bad a** female Dirty Harry in this movie called Lou that I'm about to start filming," she said, referencing the 1971 Clint Eastwood flick. "... It'll be pretty cool."
Mom airs Thursdays on CBS.