PlantFiles is getting a new look! Just in time for spring, we're rolling out a new look for the best online plants database. It will also work with your smart phones and mobile devices, so now you can take it with you on garden center visits or botanical garden tours. Questions or comments? Please post them here.
In this case, though, after blowing up the photo as much as possible, I believe it is really is shells of some sort of seed or nut, left from a squirrel's lunch... a midden, in other words. The apparent shells are all about the same size and oval (unlike the photos of Bisporella citrina below); many shell halves are sitting with the convex side up, and there are lots of piles of shell halves stacked randomly on top of each other, as well as some that have fallen concave side up or convex side up into the moss below.