That is an interesting question on Elinor.

I doubt Elinor let her emotions take over- yet she did allow her hopes to be raised by Edward's ring.
However, Elinor was resolved 'to catch every opportunity of eyeing the hair, and satisfying herself beyond all doubt ,that it was exactly the shade of her own'.
She had yet to hear Lucy Steele and from Marieanne's comment, Fanny's hair was a darker shade.
So I think at this point, Elinor made a reasonable presumption.

Actually, my image was similiar to Line's. I thought Edward at Norland, may've taken strands of hair from Elinor's hairbrush.
:)

Edward's ring is described as 'a ring, with a plait of hair in the centre, very conspicious on one of his fingers.' (ch.18)

Below, for a piece of Romanticism, I've linked a picture of a Georgian plaited hair ring which sounds similar in description to Edward's ring.

( unsure if it's a man's ring but it appears 'conspicious').