I found these on the edge of our pond nestled in the moss. 4 or 5 rows about 4 inches long, all lined up like coins. They are about 1/4 inch wide and a 1/16 thick. No visible pulp from what ever pod they were in. They were surprisingly clean, and the rows undisturbed to be animal scat, but couldn't rule that out.

These were found in the Pacific Northwest not far from Seattle.