I needed some dice for games that I am making. It was difficult to find free to use for anything dice icons online, so I ended up creating my own. I used Gimp to make the set. Nothing fancy, but may be useful for you. I just used a gradient fill and then put black dots on the squares for each side of the die.
I applied the Apache-2.0 license to these, so feel free to use or abuse them to the maximum extent possible!
Linux – keep it simple.