Chatting with Evan Rachel Wood as part of Variety's Actor on Actors series, Brown shared that her best audition was for the Wolverine film.
"I was like, 'It's going to be amazing, I'm going to really prepare,' and I sat in my room reading the lines," the actress said. "Honestly, for me, I felt so — I felt an actor, in the audition room, hitting Hugh Jackman, and James Mangold sitting right in front of me."
While the Stranger Things star didn't end up getting the role – it went to 11-year-old Dafne Keen – she did watch the film and really enjoyed it.
"I watched it, she was incredible," Brown added. "It meant so much to me."
She also recalled her worst audition, which was for a Barbie commercial when she was nine and decided to use an American accent.
"It was very awkward," she shared. "It was hard. I had to jump up and down. They gave me this, I don't even know what it was, it was just this thing I had to hold and stand up and play pretend with this other girl."
"Sometimes I thought, 'Would it throw people off of hiring me?'" she added about using her real British accent.
Up next for the rising star is the second season of Stranger Things, where she will reprise her breakout role of Eleven, and she'll be making her feature film debut in Godzilla: King of the Monsters, out March 22, 2019.
ET spoke with the actress at this year's SAG Awards about how she landed the part. "I just had a really incredible connection with the director," she said of Michael Doherty. "I had a great meeting with him and, you know, I just really love him."
"It's my first movie," she gushed. "I'm really excited and that's really all I can say, but it's going to be great!"