We shall discuss a number of collective effects arising in various environmental reservoirs. Particularly, the scattered light by a cooperative two-atom sample, in a thermostat, turns from super-Poissonian to sub-Poissonian features if dipole-dipole interactions among the scatters is not negligible. Furthermore, in a coherent laser field and vacuum reservoir of the environmental electromagnetic field, the cooperative resonance fluorescence spectrum splits in multiple spectral lines, proportional to the number of emitters from the sample. Finally, double quantum dot systems are shown to generate quantum light as well.