Not sure what the breed is...

[Gray Farms]

Della is an Easter Egger. In most cases the feed store employees barely know that they are chickens little lone what breed they actually are.

 

[NatJ]

So Della...not a Delaware after all, has finally laid her first egg...it is blue! So what is your guess on her breed. The feed store where I got her says they have never had a white Americauna or Easter Egger....so that didn't help.

She's an Easter Egger, too.
Easter Egger has become the general term for any chickens that lay blue or green eggs but don't belong to a specific breed. (Araucanas and Ameraucanas are actual breeds that lay blue eggs, but both are rare enough that you probably won't find them at the feed store.)

 

[momma chickie]

So if she meets all the descriptions that someone posted for Ameraucana how can I be sure she isn't really one. The feed store that I got her from says they have never had an all white Ameraucana or EE. She came in with a shipment with Delaware chicks. All the EE they get have been brownish red/wheat colored. Mary was in with them and she has no beard or muffs but has blue legs and lays blue eggs...so I understand the lack of muffs and beard would mean she couldn't be an Ameraucana...But Della has all the features so how do I know for sure? She has blue legs, peacomb, beard and muffs, lays blue eggs...

 

[NatJ]

The feed store that I got her from says they have never had an all white Ameraucana or EE. She came in with a shipment with Delaware chicks. All the EE they get have been brownish red/wheat colored.

Easter Eggers can be white. Just because they never saw it before, doesn't mean it cannot happen.

As for how she got in with the Delawares--if she actually arrived in the box with only Delawares, then the hatchery made a mistake. If the shipment to the store included both Delawares and Easter Eggers, then this chick either jumped into the wrong place, or someone put her there. ("What's a white chick doing there? I'll put it back where it came from" is what I think most likely.)

Of course, if they always sell the chicks before they grow up, they never know if they mis-identified the chicks (unless a customer comes back to tell them.)

So if she meets all the descriptions that someone posted for Ameraucana how can I be sure she isn't really one... Della has all the features so how do I know for sure? She has blue legs, peacomb, beard and muffs, lays blue eggs...

If she is also a color that true Ameraucanas can be, then you cannot really tell.

If she's a pet, it doesn't really matter.

If you take her to a chicken show, then she "is" whatever she looks like.

The only time it would matter if she's "really" an Ameraucana or an Easter Egger would be if you want to breed her to an Ameraucana rooster and get Ameraucana chicks. It matters then because she might also carry the gene for not-blue eggs, or for some color that Ameraucanas are not supposed to be--and her chicks might then lay not-blue eggs, or be a "wrong" color.

 

[Frazzemrat1]

So if she meets all the descriptions that someone posted for Ameraucana how can I be sure she isn't really one. The feed store that I got her from says they have never had an all white Ameraucana or EE. She came in with a shipment with Delaware chicks. All the EE they get have been brownish red/wheat colored. Mary was in with them and she has no beard or muffs but has blue legs and lays blue eggs...so I understand the lack of muffs and beard would mean she couldn't be an Ameraucana...But Della has all the features so how do I know for sure? She has blue legs, peacomb, beard and muffs, lays blue eggs...

Where does the feed store source their chicks? I would think that would be the biggest question. Otherwise, I agree with what @NatJ said. The likelihood is that she's an easter egger, and has more in her genes besides white. I doubt she'll breed completely true, since depending on where the feed store gets the chicks... there are some hatcheries that are working on snow white ee.
All that said, I have a bantam bird that if you looked at her I could tell you was a bantam ameraucana. She ticks all the boxes, but I know if I bred her she'd probably throw black chicks with lots of red, or blue with red. She's a black bird with very little red leakage that you can only see in bright sunlight. Her mother was a lavender bantam ameraucana and her father was a black breasted red bantam araucana.

 

[Gray Farms]

Where does the feed store source their chicks? I would think that would be the biggest question. Otherwise, I agree with what @NatJ said. The likelihood is that she's an easter egger, and has more in her genes besides white. I doubt she'll breed completely true, since depending on where the feed store gets the chicks... there are some hatcheries that are working on snow white ee.
All that said, I have a bantam bird that if you looked at her I could tell you was a bantam ameraucana. She ticks all the boxes, but I know if I bred her she'd probably throw black chicks with lots of red, or blue with red. She's a black bird with very little red leakage that you can only see in bright sunlight. Her mother was a lavender bantam ameraucana and her father was a black breasted red bantam araucana.

Agreed.