They look like worm castings to me.

Here is a link that might be useful: Images oif worm castings

I noticed just a few here and there last week after a brief rain. Now, after we finally got a couple inches of rain this past weekend, I have hundredgs of these little piles scattered throughout my lawn. Some areas are as dense as the pic above.

Also, sorry for the embedded pics and not links. I forget my manners sometimes ;o)

When you find casting in your yard, do you just rake them in?

I think I'll just rake them in.

From The Dirt Doctor's website (Howard Garrett):

Earthworm Castings
An effective organic fertilizer that is high in bacteria, calcium, iron, magnesium and sulfur, and it has over 60 trace minerals. Earthworm castings make an excellent ingredient in potting soil, in flats when germinating seed, and to toss into each hole when planting vegetables, herbs or small ornamentals. It is a gentle, sweet-smelling and clean organic fertilizer.

Here is a link that might be useful: Dirt Doctor on Earthworm Castings