4 eggs, from 4 different birds? Color/size comparison.

[aart]

Boy, it's gonna be hard to tell which bird laid which blue/green egg.
You'll probably have to catch them in the act.

Here's how to check pelvic spacing:
https://www.backyardchickens.com/articles/who-is-laying-and-who-is-not-butt-check.73309/

Lots of reasons for speckles, may be a new layer thing or continue(and vary day to day).

'Speckled' eggs can happen for several different reasons...very few, if any, of which are a 'problem'.
Can be caused by:
Excess or uneven pigment coating.
Excess or uneven cuticle(bloom).
Excess calcium deposits.
Porous eggs can appear speckled.
Some birds lay them consistently, some only once in awhile.
The pigment or bloom can change appearance when wet, then change back when dry again.

As long as bird is getting a good diet and is healthy in every other way, it is no cause for concern.

 

[EllieandOlive]

I've pinned down all of who lays what by running out to my barn every 15 minutes for 2 days straight! LOL also found another nest with beautiful dark olive eggs! Not positive who laid those but I have a suspicion. My little girls are all grown up!

 

[Ponypoor]

That's an awesome colourful batch of eggs!

I only have the three (so far - though apparently I am to be receiving 3 older hens from my cousin for a 'few weeks' - ya that means forever...); and as my office doorway faces the Hen House doorway here in the barn I can see exactly when my gals go in lay their eggs and then come back out hahaha. They now look to see if I am in my office working before going in to lay their eggs hahaha. Then when done they come on out march up to my door and trumpet away with their egg song... makes for some interesting Team Meeting hahaha.

Should have had chickens years ago, they are so much fun!