Many thanks to the lovely sanami276
for allowing me to convert and post her PS brushes in .gbr format. Please credit her, as I only converted them to a format usable in GIMP.
Original PS brushes can be found here
Her description of the brush set:
Crayonees, crayon doodles I made for my new layout. They are varying in size, most can used on wallpapers and headers, but they resize quite nice for icons as well.
To install, unzip files into the brushes folder in your GIMP program files (usually C:\Program Files\GIMP-2.0\share\gimp\2.0\brushes in Windows or /home/username/GIMP-2.0/share/gimp/2.0/brushes in Linux) and then restart GIMP.