The late antique philosopher Sallustius in De diis et mundo also wrote about Attis. The text is online here. I suspect this is the A.D.Nock 1926 translation, but there is an old one somewhere by Thomas Taylor.
To take another myth, they say that the Mother of the Gods seeing Attis lying by the river Gallus fell in love with him, took him, crowned him with her cap of stars, and thereafter kept him with her. He fell in love with a nymph and left the Mother to live with her. For this the Mother of the Gods made Attis go mad and cut off his genital organs and leave them with the nymph, and then return and dwell with her.
Now the Mother of the Gods is the principle that generates life; that is why she is called Mother. Attis is the creator of all things which are born and die; that is why he is said to have been found by the river Gallus. For Gallus signifies the Galaxy, or Milky Way, the point at which body subject to passion begins. Now as the primary gods make perfect the secondary, the Mother loves Attis and gives him celestial powers.
That is what the cap means. Attis loves a nymph: the nymphs preside over generation, since all that is generated is fluid. But since the process of generation must be stopped somewhere, and not allowed to generate something worse than the worst, the creator who makes these things casts away his generative powers into the creation and is joined to the Gods again. Now these things never happened, but always are. And mind sees all things at once, but reason (or speech) expresses some first and others after. Thus, as the myth is in accord with the cosmos, we for that reason keep a festival imitating the cosmos, for how could we attain higher order?