Cortinarius squalidus is a mycorrhizal mushroom found in oak-hickory forests, appearing in scattered groups on the ground. It was observed in mid to late September at Indian Cave State Park in eastern Nebraska. The species name squalidus is from the Latin word squalere means “dirty” or filthy,” referring to its overall dull brown appearance. This species lacks bright or vivid colors, giving it a rather plain look compared to many other Cortinarius mushrooms (Smith, 1944).

The cap is 1–3 inches (3–8 cm) wide, convex when young and flattening with age. It is pale cinnamon to dull brown, sometimes with streaks or watery spots, and sticky when moist. The margin may have remnants of a white veil. Gills are pale brown when young and darken with age, closely spaced, and attached to the stem. The stem is 1–2 inches (3–5 cm) long and up to 0.6 inches (1.5 cm) thick, pale and silky with a slightly swollen base. A white cortina (web-like veil) may be present between the cap and stem in young specimens. The spore print is rusty brown.