Painting Grass & Other Things directly into a scene in Maya

To paint grass or foliage directly onto a scene:

Make sure ‘Modelling’ is selected from the most upper left dropdown
Go to ‘Generate’ > ‘Get Brush’
Select the brush you want to use
Close the ‘Content Browser’ window
Now you can paint the texture into the workspace
Press B + Drag to adjust brush size
To be able to see the brush when rendering in Arnold, you must convert the brush to polygons
Select the object
‘Modify’ > ‘Convert’ > ‘Paint effects to polygons’