These are free Photoshop brushes – should work on Gimp too.  Please feel free to download them, but don’t sell them (not that anyone would want to buy them) :D

Sprinkles Brush – BRUSH | ZIP

Spooky Trees –  BRUSH (Right click > Save As>)

Stamp Brush - Download from Deviant Art

Shoe Brush - Download from Deviant Art

Short and curly hair brush - Download from Deviant Art