내 물건을 뒤지고 있었어.

A: 내 물건을 뒤지고 있었어 and came across an old journal.
B: That could be either fun or weird. How was it?
A: Flipping through the pages brought back memories.
B: Very nice. It’s your very own time capsule. Have fun with it!

A: I was fishing through my stuff 그리고 옛날 일기장을 발견했지.
B: 재미있거나 이상하거나 했겠다. 어땠어?
A: 한 장 한 장 들추니 옛날 기억이 새록새록 나더라.
B: 좋네~ 너만의 타임캡슐이잖아. 즐겁게 감상하렴!

[Additional expressions]
*I was fishing through my stuff
– I had been looking through some of my belongings / I was looking in a box
*came across an old journal
– found an old diary / discovered a personal journal that I used to keep
*That could be either fun or weird.
– That might be either a good experience or bad.
*How was it?
– How did you feel about it? / What was your reaction to that?
*Flipping through the pages
– Looking at it from page to page / Reading page after page
*brought back memories
– made me recall so many things / caused me to have some memory flashbacks
*Very nice.
– That’s great. / I’m happy for you. / That’s a pretty cool experience to have.
*It’s your very own time capsule.
– You have your private time machine to the past.
*Have fun with it!
– Enjoy it! / I hope it gives you a lot of happy memories.