Seed pods or rabbit poo?

I found these hard little balls on my weed cloth. There were also a few handsome looking seeds in the same area. When I was collecting these, I almost convinced myself they were rabbit poo.

When I was breaking them open, a few had no seeds and again I wasn't sure if it might be rabbit poo and the bunny had just been eating a lot of the same plant. Most had one seed, some had two seeds.

After breaking open 20 or so I can see all the seeds are from the same plant. The husk smells very woody, not unlike rabbit food. Doesn't smell like poo. In fact it feels nice, I wonder if it could be used as a medium to germinate seeds in. Does anyone have ideas on what they are? I had a hard time getting nice pictures, I hope they're good enough.

I'm in Zone 7B, just west of the Tulsa, OK metro area.