Furnishing the lunch room? Not so hard, really. Get AGMs with kids. We've got wood bananas, tomatoes, eggs, and so on.

To go a little more abstract, brown paper bags with names on them, containing contingency envelopes. Heck, catch me early enough next year and I'll make up sandwiches at the con suite.

On the SMS angle, I'm not sure I've seen much use of tech as a prop in a LARP - makes you wonder what folks could do if they went all-out.