Hi Dustin,
I would not use plastic-plants - they could be to hard to fold or have sharp shapes.
If you don't want to use real plants, you can take wool. I use blue/orange wool - but the animals just like the blue one. I think, it's because it's darker.
If you want to use wool, check out, that it's made from plastic. Then you have to wash it out with hot (60°C) water - to remove all traces of colour and other things that could be in it. If you offer real plants and wool, the newts will first take the plants. But if there is nothing else, they will take the wool also.
Best Greetings,
Kamil