The research project focused on investigating fungal mycelium-textile composites as a sustainable building material of the future. The mounting accumulation of textile waste, primarily cotton based materials such as denim, highlights the requirement for alternative strategies for waste minimization and sustainable material production. Mycelium, the vegetative network of filamentous fungi, has gained traction for its ability to propagate on organic substrates and form a biodegradable composite material. This study explores the potential of denim waste fabrics as a substrate for the growth of Pleurotus ostreatus mycelium through two sequential experiments. The central question was how fungal mycelium interacts with natural textiles, such as cotton, and to what extent these textiles, influence the properties of the resulting composite material. The project focused on the experimental and iterative investigation of the composites, with particular focus on observation of the growth process and qualitative comparison between different samples. The preliminary experiment investigated how configurations in denim morphology and moisture availability influenced fungal colonization. Building on these observations, the concluding experiment examined the effects of external nutrient supplementation and prior culturing conditions on microbial growth. Nutrients such as coffee and malt were evaluated in comparison with a no-nutrient control, and microbial strains previously cultured under different conditions were studied for differences in competitive colonization. The results suggest that both substrate structure and nutrition modulate mycelia growth on denim, while prior culturing condition can affect subsequent colonization performance. These findings contribute to on-going research on mycelium based materials and highlight the potential of textile scraps as a resource for developing sustainable bio based material systems while mitigating the growth of waste landfills.