Mystery egg

Last week I was watering the plants and I found an egg just laying in the asparagus patch.

Hmmm...how mysterious!  What kind of egg is it?  How did it get there?

It's small (only 1 and 1/4 inches), oblong, hard (not leathery), and white with light grey patches.  I've searched and searched for information about it but haven't found anything. 

Does anyone know what this might be?


Update:  A friend mentioned that it might be a lizard egg.  Well, I got brave enough to open it.  Whatever it is...it is definately reptilian.