Great shell. It is quite likely that this shell was originally part of a boxed set. The green hull is the usual color on these Indian shells; its the yellow one that is the more sought after. However, being a window shell, who can say if there even is a yellow example.
Regarding the Robin Hood Powder Co, information is somewhat sketchy regarding company details and dates of production of their products. Richard Iverson provides some information in his book The Shotshell in the United States. In addition, there is Robin Hood & Their Merry Shot Shells by Windy Klinect, which has some information on the company and their shells, and lots of illustrations of the headstamps and topwads, but again has limited date of production information.
To summarize, the Robin Hood Powder Company was formed in 1896 by Edward Dickson and James Ashdown to market smokeless powder developed Dickson through Ashdown’s hardware store. The powder was made in Swanton, Vt and the store was in Winnipeg, Canada. The company was organized under the laws of Vermont in 1898, adding a few partners. When they began making shotgun shells is not clear, but I assume it was around 1898. The first shells were made for the company in England, and were headstamped ROBIN HOOD No with the gauge (10 and 12 only). They soon began making their own shells with the R.H.P.CO. headstamp in 10, 12, and 16. In 1906, they reorganized under the name the Robin Hood Ammunition Company after expanding into production of metallic ammunition, and their headstamp was changed to R.H.A.Co. The company was purchased in 1915 by Remington-UMC, who used the Swanton facilities for military ammunition production in WW1.
There were no brand names for the early imported ROBIN HOOD shells. Found in 10 and 12 gauge with red, green and blue hulls. There were some later shells headstamped ROBIN HOOD 1903, ROBIN HOOD SMOKELESS, and ROBIN HOOD COMET, all with No and the gauge, and all without the arrows. In addition, Winchester and possibly Western produced some trial shells with a Robin Hood headstamp, but these were not put into production.
The following information is taken from the illustrations in Windy Klinect