Unity Forum
https://forum.unity.com/threads/best-unity-procedural-generation-tutorials.294890/

Catlike Coding
https://catlikecoding.com/unity/tutorials/

Unity Assets
https://assetstore.unity.com/packages/tools/utilities/procedural-toolkit-16508

Tree Exercise
https://gamedevelopment.tutsplus.com/tutorials/how-to-procedurally-customize-your-unity-game-assets-with-code–gamedev-12324

Maze
https://www.raywenderlich.com/82-procedural-generation-of-mazes-with-unity

https://www.creativeapplications.net/objects/simpsymm-complex-procedural-geometry-for-3d-printing/

Unity Forum
https://forum.unity.com/threads/best-unity-procedural-generation-tutorials.294890/

Catlike Coding
https://catlikecoding.com/unity/tutorials/

Unity Assets
https://assetstore.unity.com/packages/tools/utilities/procedural-toolkit-16508

Tree Exercise
https://gamedevelopment.tutsplus.com/tutorials/how-to-procedurally-customize-your-unity-game-assets-with-code–gamedev-12324

Maze
https://www.raywenderlich.com/82-procedural-generation-of-mazes-with-unity

https://www.creativeapplications.net/objects/simpsymm-complex-procedural-geometry-for-3d-printing/