There are three very popular michiinoeki(s) in the prefecture: 06-Kawaba Den-en Plaza, 11-Laran Fujioka, and 33-Mabashi Akagi,
which are among the best in Japan in terms of the number of visitors they attract.
As for specialties, there are konnyaku, Shimonita green onion, hanamame(flowering beans), and maitake(maitake mushrooms).
Another feature of Gunma Prefecture is that many of its michinoeki(s) have onsen facility.
konnyaku ... 23-Agurimu Showa
Shimonita green onion ... 16-Shimonita
hanamame ... 03-Kuni, 27-Yamba Furusatokan
maitake ... 07-Minakami Mizukikokan, 32-Ozekatashina