At eight inches long and with this distinctive bowl shape, I would call this an iced tea, or mint julep spoon, for stirring and sipping those wonderful porch 'sun-downers', preferably with the addition of a large dash of "mother's ruin" (aka, gin).
You are right, this is not sterling silver, but silverplate, a thin coating of silver applied by electrolysis over a base metal called Britannia metal, an alloy of zinc and copper with nickel added to make it silvery. For some reason, the silver coating tarnishes this odd yellow color (as well as the traditional black) when it's applied to Britannia metal.
It's quite easy to clean up with regular silver polish, or better still, by using the baking soda and aluminum foil method, which I highly recommend for all silverplate. This seemingly magic trick of kitchen chemistry actually converts the black silver tarnish back into pure silver again, rather than wiping it away as regular silver polish does.
The mark is one of the many used by the ***** ***** Silver company, when they styled themselves, "Wm A Rogers Ltd", which they did from 1894 - 1929 when they were headquartered in Ontario, Canada. During this time span, they purchased US silver manufacturers in Niagara Falls, NY and Northampton, MA. so they manufactured and distributed silverplate flatware throughout North America.
After 1929 they became part of Oneida Silver.
This mark of a +W.R. and the outline of a little vase (yes it does look like a U. Here's a slightly clearer example of it ) was used from 1894 to the 1920s, so your spoon could well be 100 years old or older.
Sadly, even though it's antique and rare, there isn't yet enough collector interest in early 20th century silverplated flatware to create much of a premium in prices.
This example of your spoon (the bottom one) sold on line (eBay) recently along with three others for a mere $10, but this is about right. If you saw it for sale in retail setting, in an antique store, say, it would have a price of about $8 - $12 on it.
I do hope this helps!
Please let me know if you would like me to explain or expand on any of the above, I would be glad to.