At relatively low polymer concentrations, granular hydrogel particles, commonly called microgels, undergo a jamming transition and behave like a soft elastic solid with reversible yielding. Over the past decade, these microgel packings have been utilized as sacrificial scaffolds to enable studies of cell behavior in a controlled 3D-environment. Here, cells can either be randomly dispersed within the microgel packings or precisely structured into well-controlled geometric shapes using 3D-printing to systematically study cell migration and invasion, differentiation pathways, collective cell behavior, and tissue/organoid development in 3D. Similar to 2D cell assays, the behavior of cells in 3D depends on the material properties of their microenvironment. Thus, controlling the macroscopic elastic behavior and the interstitial pore structures of microgel packings is critical for their application as a 3D scaffolds. Here, we present our recent progress in understanding the origins of elasticity in granular microgel packings. We prepare charged polyelectrolyte microgels with varying charge density to investigate the effects salts have on elasticity of microgel packings and relate their behavior to classic polymer physics scaling laws. In addition, we investigate the effects crosslinking concentrations have on the bulk rheological properties and the interstitial pore structure of concentrated packings of uncharged polyacrylamide microgel particles at the onset of jamming. Finally, we share our recent efforts in designing microgel particles as a transparent soil medium to enable spatial temporal studies of plant roots and plant-microbe interactions within rhizosphere.