There are two main types of photoionized gaseous nebulae that exist in the universe: H II regions and Planetary Nebulae (PNe). They mark the endpoints of stellar evolution and understanding their composition will lead to a better understanding of stellar evolution processes and galactic chemical nucleosynthesis. Elemental abundances are estimated through photo-ionization codes that include all relevant atomic processes for the plasma. Robicheaux et al. proposed that the mechanism of Dielectronic Recombination (DR) which typically occurs in plasma through free electrons would extend to Rydberg states transitioning to below threshold doubly excited states. If enough Rydberg states overlap with the below threshold excited states, then we expect a transition between them, very similar to DR; we call this process Rydberg Enhanced Recombination (RER) and it is currently not considered in modeling codes. Furthermore, it is challenging to prepare an experiment for testing RER in a lab. We investigate the implications of this new process, while also searching for observational evidence of the mechanism in astrophysical spectra. We have identified many ions that should experience RER in low temperature environments, however most of their strong emission lines are in the UV. In the case of CII, one of the terms affected by RER will have emission in the optical. In this work we present the first evidence of RER through observed optical spectra from seven PNe. We found that 2 specific lines for CII which could have RER contributions were consistently detected in all PNe. After rigorously confirming their identifications, we checked for other mechanisms competing with RER to populate these lines. We found that cascade transitions from above to these levels is also likely in these PNe. We then simulated some of the observed PNe using the Cloudy radiation transport code. We found that the emission lines are populated by both cascades and RER, confirming the existence of the RER mechanism such plasmas. We also use Cloudy simulations to investigate the effects of RER on charge state balance and temperature in PNe