Before I go on, I have to say I find the Start Menu unnecessary.  There are already many ways to get to your Start Screen:

• Throw mouse to lower-left corner (with the mouse)
• Press the Windows key (on your keyboard)
• Swipe in from the left edge (touch screen)
• Press the Start button (any device with a hardware start button)

That said, Windows is still about choice.  And here's how you can add your own "Start Menu Button"

1. Create a shortcut.
2. Type in this:
   powershell.exe -Command "Add-Type -AssemblyName System.Windows.Forms; [Windows.Forms.SendKeys]::SendWait('^({ESC})')"
   
   (all in one line)
   This sends the Windows key (CTRL-ESC) via Powershell.
   
   
3. Configure the shortcut to run minimized
   
   
4. Change the Icon, I select this icon from the bootux.dll file %SystemRoot%\System32\bootux.dll) 
   
   (All the icons are white, select them to see what they look like) 
   
5. Drag the shortcut and pin it to the task bar, on the far left.
   
   
6. Now you have that familiar Start menu button back.  Click it and you'll get the Start Screen to pop up. 
   

Notes

• Does not appear to work in Windows RT, but if you have a Surface just hit that start hardware button