someone said they are lamb's quarters. I wonder if what I planted are actually wintergreen seeds!

What's coming up sure as heck isn't Gaultheria!!

Callisto, no, not gaultheria seedlings. How have you conditioned your seeds? Gaultheria procumbens will generally germinate best if soaked overnight, then given 8-12 weeks moist chill (40ish F), could take an additional 2 months or more to germinate when brought back to approx. 65 F.

Lamb's quarters, poor man's spinach, or a number of names, it looks like Chenopodium album to me.

tj

Here is a link that might be useful: Link to your pic