I think
www.marcospapers.com has some. It's called "duplex cardstock." Usually it's a textured cardstock, but not always. I have some that's forest green outside and white inside, and it's really pretty! (Not that I've even seen it in my room for years...stuff builds up over time, lol!!)
If you have a Paper Plus in your area, they used to have some, last time I was there, anyway.