Living in SF, it's easy to find most Mexican, Latin American and Asian ingredients. But, there are a number of items easily found on the East Coast (where I grew up) which I can't find here.
premium sliced bread (like Peppridge Farm or Arnold’s)
spaetzle (Maggi, boxed)
hominy grits (slow, not quick)
pasteurized eggs (occasionally but very rare)
cappicola (ham from the shoulder)
I've lived in the SF Bay Area for 14 years... I can help you out with some of these...
Arnolds brand is called Orowheat on this side of the Rockies. The labels look exactly the same except it says Orowheat rather than Arnolds. They sell it at pretty much every Safeway in the area.
I've seen Radaitori pasta at Whole Foods Market, Lunardis and pretty much every other high end grocery store.
Spaetzle and real Hominy grits I've seen at Lunardis.
Pasteurized eggs are available at pretty much every big chain grocery store (Egglands Best)
Cappicola ham, I've seen at Whole Foods, some Safeways and the deli section at Lunardis.