Every seed I have ever heard of needs to be dry before harvesting. But new Rosemary plants are best gotten from cuttings. The seeds have a very low germination rate from all I have read. Not only are cuttings easier but much faster. But then the fun is in having success starting anything from seed so let the venture began

This is a Seed Saving question and they have their own forum here. It is direct linked near the top of this forum's page.

But the basic answer is no you cannot. The seeds will still be immature and non-viable. They have to mature on the plant.

Dave