How do I change or eliminate the flower on the upper right corner of my emails in Mail?

Change the contact picture associated with the sender.

Is this person listed in your Contacts? If not, go to Applications --> Contacts and add them. You can change their image from there. 🙂

Can you post a screenshot? When you say there's no image there, is there literally a blank spot or something else?

One, you shouldn't have shown the whole image, because now everyone will get both your phone numbers and your e-mail address. You should have cropped it. Two, hover your cursor over the "Add Photo" circle. Do you see the word "edit" on it? If so, click on it. You can then add an image.

This is the image associated with your account, probably the first time it was created.

If you did not associate any picture in Contacts, as you say, then you can add one there, or change the flower to something else in System Preferences->Users & Groups.

Don Rex wrote:

I also added the same image in Users & Groups.

Two things that occur to me:

1) Are you sure that the entry in Contacts is definitely the one the system associates with you?

(In Contacts, Card->Make this My Card should be greyed out when your card is selected; there should also be a little person-shaped badge next to the name:

2) That flower image may still be cached somewhere, possibly by Mail itself. If that is the case, rebooting in Safe Mode, and then booting normally again may do the trick.

After all of that, are you aware that the image isn't "attached" to your email? Mail just tags the message with the sender's picture from Contacts as you view it. The image is not sent or received by anyone. Only you can see it.