Assuming that you are not located in one of the few states that has adopted the Uniform Unincorporated Nonprofit Association Act (See Ready Reference Page: “Revised Uniform Unincorporated Nonprofit Association Act Provides Rules of Conduct”), which might have provided some ground rules for protecting your personal interest in operating the association, you probably don’t have any legal rights in this situation. Any group that wants to can incorporate a nonprofit corporation.  And even if you had some procedural rights in an association, it is hard to imagine what you would accomplish if you decided to pursue those rights.  It is unlikely that you could undo what the others have done.  Even if you could force them to take a new vote, they could outvote you to ratify what they have done.  And would you be willing to pay the costs involved when you were unwilling to use the funds of the group to pay the corporate filing fees?

It isn’t surprising that the other three incorporated the new entity without you if they thought you did not agree with what they were doing.  As the incorporators, they would ordinarily have the authority to name the initial board and would have had the power — and reason — not to name you to that board.  Your question now may be whether you are — or can become — a member of the organization so that you can participate in its activities and, if the group has voting members, vote at the next election for new board members to run the group.