hi 7asho0m, and welcome to sevenforums,
in windows-speak, that's called a start-orb.
there are quite a few custom ones in this thread
- have a look - or have a good google.
there's a link to a tutorial on how to change the orb/button image in the first post of the thread.
...and if you can't find exactly what you want, you can always ask one of the graphics team to make you one.