I just wrote a code that creates a window (using TKinter) and displays one working button.
b = Button(master, text=\"get\", width=10, command=callback)
astynax is right. To follow the example you gave:
MyButton1 = Button(master, text="BUTTON1", width=10, command=callback)
MyButton1.grid(row=0, column=0)
MyButton2 = Button(master, text="BUTTON2", width=10, command=callback)
MyButton2.grid(row=1, column=0)
MyButton3 = Button(master, text="BUTTON3", width=10, command=callback)
MyButton3.grid(row=2, column=0)
Should create 3 row of buttons. Using grid is a lot better than using pack. However, if you use grid on one button and pack on another it will not work and you will get an error.