Joshua Goldberg, 20, has been charged with distributing information about explosives and weapons of mass destruction.
The FBI said he planned multiple attacks in the US and Australia, posing as an Islamic militant from Australia.
He was arrested after suggesting a bombing of a 9/11 memorial.
A judge ordered him to complete multiple evaluations, including one of his sanity at the time of his arrest.
He told a prison psychologist he wanted to find terrorists online because he wanted to join the FBI or become a journalist.
The psychologist deemed he is on the "schizophrenia spectrum".
While in a detention centre, he was unstable and put on suicide watch.
Talking to an FBI informant online and using the online name "Australi Witness", he sent bomb-making plans and said the informant should target a 9/11 memorial in Kansas City, Missouri.
Pressure-cooker bombs were used in the Boston marathon bombings that left three dead and dozens hurt.
In other instances this year the FBI has charged American residents with plotting terrorist attacks after finding them online.
"What weapons do you have brother? I can send you guides on how to make bombs if you need help making them," wrote Mr Goldberg in one message to the agent.
Mr Goldberg sent bomb-making guides to the agent on 19 August, asking the agent how he wanted to attack on 11 September.
A US judge has ruled that a Florida man accused of plotting an attack on a 9/11 anniversary is not mentally competent enough to stand trial.