Another option may be available from your own disciplinary community. Many groups of scholars have been collaborating to collect and publish open education resources. An example of this includes Chris Stieha's publications at the EcoEd Digital Library and in open access journal, CODEE journal
Other examples are the Open Social Work project and the Open Geography Education project. There are also cross-disciplinary efforts such as the Rebus Community. Each of these will have their own criteria for participation so "your mileage may vary". But if you and your content are a match, it can be a rewarding and supportive experience.
Try browsing the list of sources indexed by the very popular OASIS OER search tool. You may find that you are already affiliated with an organization that does OER publishing.