If you're looking, as a woman, to have multiple male partners, that is not at all uncommon. If you're looking for a MFM triad where all partners are intimately involved with each other, that seems rarer. So, which are you after, or would either be cool?
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.