Looks like some type of cup fungi.I kind of imagine them being Bisporella citrina,though it's very difficult to determine what from that photograph and the amount of information given.

Are they growing from bits of woody debris,or peat,or directly from soil?

Also posting a good large macro photo would help as well.

Chances are that the spores will not adversely affect your health,but some folks are sensitive and may become sickened.

These things are impossibly small. My camera will not have much more detail that what you see. Most of them are less than a millimeter in diameter. They appear to be growing just on the top of the soil. The soil had a good bit of wood debris, so they could be on these wood shards, but they seem to not care. The went to spore after 7 days of first appearing, and then spored again the day after. Seems any disturbance in the air triggers it.

All I can think is that they are either in the genus Bisporella or Tarzetta.