Upvote:2
The Second International Conference on Patristic Studies will meet in Argentina in March 2017 with the purpose of discussing “Late Antiquity manuscripts found during the 20th and 21st centuries.” These include “the Nag Hammadi Gnostic library, the Dead Sea Scrolls, Origen of Alexandria’s homilies, Augustine’s sermons, etc.,” so the 21st century discoveries they reference might well include newly-discovered literature from the ante-Nicene period.
Inquiries to The North American Patristics Society's Facebook page or Stack Exchange’s History site might offer better access to expertise in this field. Good luck!
Upvote:4
Yes. 29 homilies of Origen were discovered in 2012 in the Bavarian State Library in Germany. Some of them were already available in Latin translation, but others were completely new discoveries. Origen scholar Lorenzo Perrone judged them to be genuine.
In 2015 the homilies were published in a critical edition, the front matter of which is available on academia.edu.
Several years prior, in 2008, six sermons of Augustine were discovered at Erfurt, in a 12th century manuscript. Larger groups of Augustine's writings had also been discovered in 1974 and 1990.