I’ve never encountered them as a playable race/class in 3.5 or Pathfinder. I was able to find some homebrews, though.
Here’s a homebrew Scarecrow class for D&D 3.5 .
A quick google search turned up this homebrew of a Scarecrow Race for 5E.
Ask your DM if they’re okay with letting you run homebrew content, of course! They can also help you tweak these to fit whatever version you’re playing.