Ashtvinayak are eight holy self made (Swayambhu) idols of Lord Ganesh. All of them are in Maharashtra, namely Chintamani, Siddhivinayak, Vigneshwar, Ballaleshwar, Varad vinayaq, Mahaganpati, Mayureshwar and Girijatmaj. I want to know which scriptures describe them and how.
Girjatamaj in Lenyadri (Shree Girjatmaj Vinayaka-Lenyadri) refers to the first of the eight Ganesha temples part of the Ashtavinayak pilgrimage.—In Maharashtra (a state in central India) there are eight revered temples dedicated to Vinayaka (eight images of Ganapati). [...] The names of the eight kshetras (shrines) [viz., Girjatamaj] are listed in the mangalashtaka-sloka. This sloka is always recited during a religious ceremony. [...] The Ashtavinayak pilgrimage (visiting the eight shrines of Ganapati) is believed to guarantee eternal bliss. That is why many want to do it at least once in their life.
Ashtavinayaka temples [viz., Girjatamaj] are ancient, they are mentioned in the texts of Ganesha Purana and Mudgal Purana. However, most of the kshetras (shrines) were rebuilt and restored during the reign of the Peshvas (supreme rulers of Marathi).