So arguably the greatest mathematician of all time[2] wanted a particular tribute to something he did while a teenager, felt was one of his greatest achievements (because the problem had been unsolved for over 2000 years) and someone just decided they couldn't be arsed.
The whole thing is described really well here, including showing the full construction https://www.youtube.com/watch?v=EX7U0DGBmbM
[1] Picture here https://www.atlasobscura.com/places/grave-of-carl-friedrich-...
[2] My vote would go for Euler, but a lot of people feel Gauss.
But there's a statue with that star (https://de.wikipedia.org/wiki/Carl_Friedrich_Gau%C3%9F#/medi...)
But per below comments, the star is on the monument in Brunswick/Braunschweig, not on his headstone.
An image search for "gauss monument brunswick germany" on Duck Duck Go includes a picture of the 17-point star at this link:
https://www.braunschweig.de/leben/stadtportraet/stadtteile/n...
I can't go to it to confirm because we are blocked from going to foreign links at my work place. It looks like the star is on the left side of the monument near his right foot.