Good find, Roger.
What is the size of this weight? I guess that it could be roughly 2/3 that of a magnum weight shown in Hollister's book (1st edition) - see below.
I assume your copy of Hollister's book is a second edition. In the 1st edition there is less comment but there is a statement that earlier Port Elizabeth "rare bird weights", using powdered glass "probably placed on a metal or a wooden die", were a "prototype for the later Millville weights featuring pictures".
The comment about the Millville 'picture weights' includes a reference to Fig. 212 and Col Fig. 114 [ * ], which show a magnum size weight [but actual size not given] with the same form of coloured border as on your weight. The floral parts of yours are (mostly) an exact match to the upper part of the magnum weight in the book, which is a very full floral display in a substantial basket.
[ * ] For Col Fig. 114 the caption states, "Port Elizabeth or Millville ...". So it looks as though there was uncertainty at that time about the magnum weight shown actually being one of the "later Millville weights featuring pictures".