Emerging pervasive computing technologies such as sensor networks and RFID tags can be embedded in our everyday environment to digitally store and elaborate a variety of information. By having application agents access in a dynamic and wireless way such distributed information, it is possible to enforce a notable degree of context-awareness in applications, and increase the capabilities of interacting with the physical world. In particular, biologically inspired field-based data structures such as gradients and pheromones are suitable to represent information in a variety of pervasive computing applications. This paper discusses how both sensor networks and RFID tags can be used to that purpose, outlining the respective advantages and drawbacks of these technologies.