Would there be any way for a poly group to get married with one another?
Legally, no, there is no way for more than 2 people to be legally married in America. There is, however, nothing preventing you from having a big ceremonial party, referring to each other as your spouses, or living together.
Some polyamorous families have formed LLCs or used other creative workarounds to handle issues around finances, property ownership, health insurance, child custody, etc. Check the resources here and here, and consult with a poly-friendly lawyer in your area.