Both YottaMark and FoodLogiq offer systems that let shoppers type a textcode into a mobile phone or home computer, or scan a bar-code using a phone's built-in camera, to find out when the tomatoes on the shelf were picked and which field they came from.
The source code for the existing Silent Text version is here and the company tells me that the new Silent Text source code will be released sometime in March or April after confirming legal issues such as licenses for third-party libraries.
If you have already created code for laying out labels according to the bottom or center point, your text will move around a little and you will need to adjust your constraints.
Source code can also be distributed in text-based form like a PDF or scanable book which is what MIT did for Phil Zimmermann and later what 70 international volunteers did for the PGPi Scanning Project in 1997.
Some of them rely on technology other than NFC, such as offering services that let people pay for purchases by sending text messages or by scanning product bar codes using a phone's QR-code reader.