They look to me like seedlings of probably spruce, possibly pine.
-Don

I take the lack of responses to mean it's not obviously some sort of carnivore who snuck into there.
Not a pine seedling:
{{gwi:548161}}
yes they look similar at this stage.. But I plucked a leaf & there's no pine scent or taste.

Gonna let them grow for a bit- Very curious as this 'dirt' mix hasn't been exposed to any extraneous wayward seed sources (stored outside, etc) I'm fairly certain.

I imagine even without the scent it could still possibly be a pine. The seed looks exactly like one as does the seedling, but I'm not sure when they start smelling like a pine. It could also be spruce, fir, or any needle-y conifer. But it definitely is a conifer, in which case I'd leave it because the needles will help acidify the soil if you keep it around that long. Free mulch!

Your best bet: wherever the pot is/was, look around at the trees and see what might have dropped in.

Definitely?
Here's some new pics:
{{gwi:548162}}

{{gwi:548163}}

Conifers don't branch before the 3rd or 4th year of life.. Nor do they flower.

I've realized I may have sounded a little pointy there. Here's why.
The first 30 years of life I spent in the middle of a million and a half acre National Forest. The Plumas, to be exact. Primary summer jobs? Faller (guy who cuts trees) for said National Forest.. And Sawyer on the Plumas Interagency Hotshot Crew.

Thus at this point I have more "in the woods" time... Than most people have spent in their own house.

So I have absolutely no doubt it's no conifer. What is it? Not a clue. Doesn't look carnivorous. If it was covered in dew like my baby byblis, well that would be easy. But it's not.
Maybe when those flowers open...

A WEED

Exactly. Nothing more than a lil green flowered weed. So I pulled 'em all.

could be a weed, or possibly a carnivorous plant that does not seem carnivorous until later periods in its growing stage.

yeah i get these in my pots and i just pull them out. sphagnum grows nice in carnivorous plant pots and i have a few neps with moss and small ferns in with them. which i leave!

Just pull it out. Most crap that grows with your CP's will have a larger root structure than your CP's (esp. since most cp's have small roots) so they will negatively impact your plants.