What can I offer to Odin?

I just recently started my first ever altar and I don't know what to do. My altar is for Odin and I currently only have a rib bone with his rune carved into it and a jar of chamomile. I don't entirely have all 9 of the sacred herbs and I was wondering what I could use as substitutions. I know flowers are also a good offering but I don't know what flowers would best fit Odin.