Today I got the green ring AND the 1st gen ring both in Oos using tha gasha ring at the ancient ruins. I kept using the gasha ring at the ruins soil and got these results:

Dbl edge ring x3
Rang ring lv 2 x2
charge ring x3
bombproof ring x2
green ring
1st Gen ring
Masters ring

These are all fairly rare rings (some REALLY rare) and i am pretty sure that most are only available at this soil.

Comments anyone?