For US tax-exempt contributions of over $100 you can donate via New Israel Fund: 

Preferably by check: Checks of $100 or more can be sent to:
The New Israel Fund
PO Box 70358, Philadelphia, PA 19176-0358, USA.
In the memo line, write:
“Donor Advised for Gun Free Kitchen Tables” 

By credit card via NIF, for contributions of over $100:

please use the “Give in Honor“ option offered on NIF’s homepage.
The “Honoree Name” is: Gun Free Kitchen Tables;
the address for notifying us is: gunfreekitchentables@gmail.com).