A big congratulations to those accepted into the class of 2020! A pretty minor concern here - wondering whether admitted students will receive a complimentary T Shirt and other merch (since most other colleges seem to be in the habit of mailing these items to admitted students). Or would we have to go to the Admit Weekend to get them?
In the past I don’t believe so - you do get free swag and shirts once you’re a student and during NSO (New Student Orientation).
@Lagging Omg, wish I knew that before I ordered literally $170 of swag online. OOPS.
Hah! Been there done that. The free swag at NSO is usually your class year’s t-shirt (which someone in your year will design, so you won’t have to worry about having duplicates of that). During the year if you go to the earlier football games you also can get more free swag (non-class specific). Other athletic events also give out swag as well as other Stanford-related events throughout the year. Mostly it’s shirts (sometimes lanyards, water bottles, etc.). Most students still buy a few things from the bookstore to supplement so I doubt you’re alone.
If I remember correctly you get a “Stanford Admit Weekend Shirt” if you go to Admit Weekend. You get TONS of free t shirts/swag once you’re an actual student here. The free shirts that Yale and Princeton gave me I threw out 
At my high school, the guidance counselors would invite college representatives for the top students to come for graduation (this was popular with a lot of the big state schools) - of course nobody from Stanford came, but they did send a pennant and a car decal by way of apology. 