Disclaimer: While the relatively few places near SLAC are easy to point out, there are 200+ restaurants in Palo Alto and Menlo Park area which are within 15min of drive, and many are good lunch places. The list here is therefore from a rather limited sampling knowledge to just point out a few more commonly known around SLAC, while you should consult more general guides such as Google Maps, or yelp which have more reviews for many places (also check Palo Alto, Portola Valley). If you are really interested in the broad range of restaurants but challenged by transportation, delivery by Waiters On Wheels for a collective order may be another option. Below are some suggestions for nearby places for a simple lunch (plus just a few places a bit further out from choices of many). Click on the full screen mark on top right corner to view larger map. Click on individual places for more info.
Extending topic to dinners, the above disclaimer applies even more strongly as it becomes a rather subjective choice. For those who really don't want to think about it, there are some specific recommendation lists you are welcome to consider:
which maybe not all up to date, as some places such as Round Table Pizza, Hunan Gardens and Zibibbo are now closed.
Note that US restaurants (and shops) list item price before tax and a 9% sales tax will charged on top of the listing price. In addition, tips to services are not included in the price in most cases and you are expected to "voluntarily" add roughly 18% of the total cost before tax as a tip in case of sit-in dining at restaurant served by a waiter/waitress (their wage largely come from that), which can be cash left on the table or written in to credit card bill.