Chicks, Westmoreland
This 7-inch blue plate has the mark with the words Westmoreland in a circle around a stylized "W," which they started using in the early 1980s. Still, some reproductions of Westmoreland glass have this mark, so I'm not convinced this was made during that period. This is the only example I've seen; it sold on eBay in 2003 for $11 although I suspect they could be worth a bit more.