Glass Oil lamp Pattern, Depression glass?

I looked in my glass books and couldn't find anything that matches and was hoping someone here might have seen this pattern before. The base itself is 8" tall and as you can see it is aged and has a yellow tint to it. The burner is plain with no markings.
The base has no collar attached as the burner screws directly onto the glass.
Anyone know how old this is?
Mikey

 

Sunflower? Is there a manufacturers name on the dial?

 

No marks at all on the burner and dial.
Mikey

 

Just to clarify, all the metal here is connected, and screws to threads that are molded into the glass?

 

Yes

 

I've seen a few "collars" like this one on newer oil lamps that resemble antique lamps. I don't know of any US glass houses that were doing this kind of work.
Probably later 20th century