Asking where to find a headshop in San Francisco is like asking where to find a hair on Danny de Vito's back.
i don't remember the name of it but yes they allow you to browse and buy no questions asked, they could care less. All i remember was it was the last head shop on the left side of the street while facing golden gate park.
day dreams (or day dreamz? can't remember.) its at 1589 Haight St, its sort of in the middle of the haight, if that makes sense if you look 18 they probably won't ask for ID, but if they do i usually just say i don't have one on me and that i come in all the time - they usually don't care though