Most likely slow-release fertilizer. Can you post an image so that it can be verified?

If these were "fertilzer" they would be of uniform size, not varying from pin head to pencil eraser size. If that is "fertilizer" it must be listed on the bag as an ingrediant.
I cannot imagine a supplier adding a "fertilizer" to "topsoil" although because most "topsoil" is what is scraped off somewhere the possibility of insect eggs is very real. It would be difficult to say, even with a picture of those, if they are eggs and which insect they might be eggs of.

Who knows what people do these days. Perhaps a garden helper is involved?
Beyond that, my bag of Osmocote has variously sized "eggs."
Also, "topsoil" comes in bags, especially at home depot.

Please post a picture. Without it, all will be wild guesses.

Lacking that, take a sample to your county Extension Service office. (Use this USDA site to locate it: http://extension.wsu.edu/locations/Pages/default.aspx)

Here is a link that might be useful: Extension Service offices in WA