Mushrooms are a significant component of human diets but can bioaccumulate hazardous substances, including both anthropogenic (¹³⁷Cs) and naturally occurring (²³⁸U, ²³²Th, and ⁴⁰K) radionuclides. This study quantified these radionuclides in 24 commonly consumed mushroom species collected in Amasya and Tekirdağ, provinces of Türkiye. Using a high-purity germanium (HPGe) detector, we found ¹³⁷Cs activity in the Tekirdağ samples ranging from 3.9 to 127.8 Bq/kg, while the ¹³⁷Cs activity in the Amasya samples ranged from 3.1 to 63.7 Bq/kg. In particular, Tricholoma terreum (Tekirdağ) and Tricholoma imbricatum (Amasya) exhibited notably higher ¹³⁷Cs concentrations. The concentration of ²³⁸U varied between 4.8 and 17.5 Bq/kg in the Tekirdağ samples and 6.5 and 16 Bq/kg in the Amasya samples, whereas the ²³²Th and ⁴⁰K values fluctuated across species and regions, with ⁴⁰K sometimes exceeding 1900 Bq/kg. These results highlight that mushrooms can serve as effective bioindicators for residual radioactive contamination and underline the need for periodic monitoring to assess potential public health risks associated with wild mushroom consumption. These findings also offer a valuable dataset for understanding post-Chernobyl fallout dynamics in the forest ecosystems of Türkiye.