First....congratulations on great purchases at great prices! That twisted stem piece would easily bring $300USD on eBay. I wish I could shop where you shop!
I have to agree with Bernard C. The tazza could have come from any of the glass houses in the Stourbridge region. Richardson, Powell, Webb, John Walsh Walsh, Stuart, or Stevens and Williams all had the skill to make it, and did.
the two little blue baskets are, of course, Davidson.
You also later showed a larger primrose pearline bowl, which has commonly picked up the pattern name of WILLIAM AND MARY. It was an extensive pattern.
The photo you showed of the grouping of three of the website I administer was sent by one of our members, and that person most likely would also just say the pieces are Stourbridge Glass. Not only did all of the factories copy each other, but the workers were not stagnant either. They went where the work was, wherever they thought the grass was greener, and moved from factory to factory.
Unless there is excellent provenance (handed down through a family with roots at a particular company), the best you can do with art glass is 'Stourbridge region'.
Some of the companies had line drawings and some of that material can be researched in current publications. For instance, the book on John Walsh Walsh has a bunch of design patterns shown. However, that does not mean other companies did not copy work, or even that John Walsh Walsh copied someone and added it to their design book!
If you want to double your money on that tazza, I can send payment immediately! Way to go!
aka Mr. Vaseline Glass