Indoor shredding ideas for puppy who eats paper and cardboard?

My eight-month-old puppy seems to love shredding things, but unfortunately eats paper and cardboard as she shreds. She didn’t do this when she was very little — she seemed to chew and spit it out — so I wonder if maybe it’s because I threw out the little bits of cardboard she scattered around the house… but in any case I can’t figure out a way to stop her from eating it. I gave her a piece of paper towel this morning and she ate half of it in about thirty seconds. She isn’t a very hungry dog and often ignores meals and treats (I’ve spoken to my vet about this twice and he’s not worried, says it’s common for terriers) so filling up on paper really doesn’t seem ideal! When she’s outside, she shreds bark and sticks (and seems to spit these out) and is so happy, but it’s not really practical for her to do this indoors. Does anyone have any ideas on things my puppy could shred indoors instead of paper and cardboard? I’ve given her lettuce, and she liked that, but keen for options that are a bit easier to clean up (the lettuce gets her bed all wet if I don’t clear it up right afterwards) or just as another option so she has variety!