I would completely freak if I found a Tarot deck in my bag. I'd think one of my kids slipped it in there or somehow it got in there when I was in one of my usual hangouts: bookstores and metaphysical shops. I'd be driving around town asking stores if it belonged to them until someone claimed it. I would not be able to relax with merchandise I did not buy that I found in my bag. (Yeah, I'm the type that *never* shoplifted as a teen, either.)
One time when my older son was a baby, we got out to the car and when we were folding the stroller, there was a book in the bottom that I'd been looking at but decided not to buy. Even though I took it right back in, I felt terrible that I'd unintentionally taken it without buying it.
That said, one day in geometry class at age 13, my books wouldn't fit under the desk and I reached under to find out why and pulled out Richard Bach's A Bridge Across Forever, which said it was a "love story" so I took it home and read it. It talked about things I'd never heard of, like astral projection and all sorts of new age things. I took it back to school and gave it to the girl who'd written her name in the cover, but reading it really opened up my world.