Hi Tammy,
Your Midwinter willow probably dates from around the 1940s. Made in England, it's a nice pattern, but not too rare. As for value, it depends on what pieces you have. Plates might be from $5-10, vegetable bowls $15-20, etc. All willow is collectible! And there may be people out there trying to build a set of this maker, you never know.

Jeff