Combining different fundamental excitations is a recent route for quantum computation applications, with the promise to stimulate the development of new hybrid quantum technologies and protocols. In this frame, magnons exhibited strong stability in coupling with photons, when they are excited in ferro/ferri-magnetic (FM) materials, especially if Yttrium Iron Garnet (YIG) single crystals are used. In our labs, we investigate the interaction among the magnetization precession modes, in a small magnetically-saturated YIG sphere, and the MW electromagnetic modes, resonating in a tridimensional aluminum cavity, at room temperature. A rich spectrum characterized by several anti-crossing features is observed, because of the strong coupling regime in correspondence of various magnetostatic modes. Time-resolved studies show evidence of Rabi oscillations, demonstrating coherent exchanges of energy among photons and the involved magnons modes. For facilitating the analysis of the stationary spin-wave patterns, here we propose a new procedure, based on the introduction of a novel functional variable, related to the magnetic characteristics of the FM material and to the applied external electromagnetic field [Leo et al., https://arxiv.org/abs/1905.01522].