Why isn't Shimson's mother named in Pesukim that tell the story? She is featured rather prominently, and the angel appears to her before speaking with both her and Manoaḥ. It would stand to reason that she is as important a character as other barren mothers who prayed for children and were blessed with great leaders for sons. (Aside, to preempt comments comparing Shimson to some of those other leaders: Perhaps he wasn't the greatest leader or a true Navi, but he was great enough for his story to appear in TaNa"Ch, and it's not like his father isn't named.)
To answer the minim (people who deny the oral Torah) because the names of important people such as Dovid's mother or Avraham's mother is also not mentioned in the Torah is brought down through oral tradition which minim do not have(based on Bava Basra 91a).