You can find the group's star on the Hollywood Walk of Fame at 6675 Hollywood Boulevard, right outside of the Vogue Theater. The Vogue just happens to be where Head premiered in Hollywood on November 19, 1968.
This photo of the Vogue marquee was taken on July 10, 1989, the day The Monkees received their star:
And here's a photo of the Vogue marquee on the night Head premiered:
In Memoriam: Michael Nesmith
Dolenz sings Nesmith - The EP