I'm building a home for a Plantsim shaman, and I want his shelter to disappear into the trees as much as possible. Ideally, I'd like it to be covered in greenery, such as ivy or vines. Is there anything like this available anywhere? Or a rooftop garden effect, for a flat roof?

Hey, BlueAlien! I got a bunch of results just by putting the word "ivy" in the search box that shows on the right side of the pop-down menu when you click on the word "Download" in the navbar at the top of the screen.

Looking through those, actual walls made of or covered in ivy are not that easy to find, but you have several choices of climbing plants that can be made to come up or down your walls nicely. I picked out some of the ones I thought looked nicest for you:
Wisteria
Climbing ivy converted from TS3
More ivy either crawling up or hanging down the wall.
Also, there looks to be some in this garden set.

And like I said, you can always repeat the search I did to see if there's anything more, or maybe instead enter words like "vines," or click on the tags on some of the cc I've linked already.

Good luck!

Thank you, @natboopsie! These are great!

Oh, good! I'm so glad. I mean, I think I did spot a couple walls with ivy already on the panels, but it sure looked repetitive and unnatural. Hopefully those will give you a lot more choices and ways to make the lot look lush and organic! Love your idea.