A mycelium is a network of hyphae that possesses the ability to self-assemble and grow into various shapes, acting as a natural binder that minimises the need for intensive chemical and energy processes, making it an alternative capable of forming structures that may eventually outperform traditional fibres such as animal leather and polyester. In this work, two mycelium mats were created, and their thickness, water absorption, coverage, and tear strength for the sewing process were determined. Fibre mats were grown in vitro or on a jute substrate. The mats were treated with salt, tannin or citric acid solutions, then air- or oven-dried. In general, the treatment that least modified the colour and appearance of the mycelium mats was citric acid, and when dried by airflow, the thickness averaged 1.4 mm. The highest tear strengths were 10.55 N/mm and 12.7 N/mm for the mycelium mats treated with citric acid without and with jute, respectively. A high percentage of water absorption was observed, reaching 267% (mycelium mats treated with tannins and dried at 65 °C) and 28% (mycelium mats treated with citric acid and air-dried). In general, all mycelium mats can be sewn, except for those treated with citric acid, which have a viscous texture and require slow sewing to prevent the mycelium from breaking. The Trametes fungus can be utilised in the production of mycelial materials, allowing for the optimisation of growth conditions to obtain mycelial mats that meet the requirements for use as an environmentally friendly alternative in the textile and related industries.