Mason's Patent Ironstone China Plate

This beautiful plate was found in my grandmother's house.  On the back of the plate in a reddish colored stamp, I see Mason's with a crown followed by a banner that indicates the plate is "Patent Ironstone China".  In the same color to the right of the mark is the letter B.  Impressed in the china are 4 words.  The first word I cannot read.  The following three words are "Real Ironstone China".  Above that is underlined 2/99 also impressed in the china.  Beside that is the impressed letter O.  In orange, there appear to be some handwritten letters and numbers.  A is the first line.  3911 is the second line.  6 or u is the third line.

The front of the plate has beautiful orange and black flowers and leaves with beautiful gold accents.  The scalloped edge of the plate also has gold trim.

I'd like to know more about this plate and if possible, it's current value.