Do you already have a 501(3)(c) nonprofit? Or, are you browsing now to make plans? The sites below offer general overviews and detailed lists of possible grants available to nonprofits.
Need an overview of the grant process for your 501(c)(3)? This site has information on that and other topics.
Here is a video about the grant process by Purdue University. Click on the resources tab in the middle of the page. They also have in-person classes on grant writing.
Your local library may have resources online and onsite. Here are two examples of libraries that have helpful information on the grant process plus some funding sources.