Here's another way to find grants: If you don't see a grant opportunity that fits your funding need, consider submitting an unsolicited proposal to one of the many U.S. federal agencies that accept them.
It is the policy of the U.S. government to encourage the submission of proposals that contain new ideas and innovative concepts pertaining to agency program areas. When a new, innovative idea is overlooked by agency-initiated funding opportunity announcements or does not fall under-publicized topic areas, the idea may be submitted as an unsolicited proposal.
An "unsolicited proposal," as defined in the Federal Acquisition Regulations (FAR 2.101)
is a written proposal that is submitted to an agency on the initiative on an offering individual or company for the purpose of obtaining a contract with the government that is not in response to a request for proposals, broad agency announcement, or any other government-initiated solicitation or program.
Unsolicited proposals are welcomed by most agencies since they allow companies to demonstrate how new ideas, innovations and projects, which do not fit with current grant, loan or loan guarantee opportunities, tie in with existing agency programs and advance agency missions and, therefore, are deserving of agency support