“Laser test paper” is, of course, intended for testing lasers, but I thought it might make a outdoor plant tag. A while ago I tried some Trolase Thins acrylic for that job:
Which turned out to be entirely too stiff, which wasn’t surprising given that Trolase Thin is intended for signage stuck on flat or slightly curved surfaces.
Despite being “paper”, laser testing paper is also too stiff:
The wrinkles and cracks on the left end of the tags shows the plastic coating makes it basically impossible to shape / bend the paper enough to wrap around a plant stem, then push it through the hole (offscreen to the left). I was not surprised too much by this discovery.
Those two strips now hang outside the kitchen window (left end upward), where they’ll get enough sun and rain to keep a plant happy, and I’ll see how well the engraved / damaged plastic coating stands up to that sort of abuse.
For Science!
The Smell of Molten Projects in the Morning 
Maybe tyvek would work for the purpose.
Tyvek is a single layer of HDPE, which would likely melt rather than char into a visible pattern, but I’ve often been surprised at how stuff lasers. I must try engraving a Priority Mail envelope …