Someone asked the question on Yahoo Answers, How do you find out what a mug is worth? This mug is green and marked in the bottom with a letter H in a circle and has the number 497.
One way to estimate the value of collectible mugs is to look on eBay and other on-line sites where collectibles are sold. There are many different types of mugs and you have not given enough information.
Another way to access value of a collectible mug is to look the mug up in books devoted to giving values to mugs and other collectibles.
See the book "ABC Plates & Mugs Identification and Value Guide: Identification and Value Guide (Hardcover)"
The markings that you describe tell the batch number when the mug was made. But other important factors are the style, manufacture, material that it is made of (i.e. glass, china, plastic, etc.), time period that it was made, etc.
Your mug might be an Anchor Hawking mug which is collectible. But without knowing more about it that is just a guess.
The main thing to consider with all collectibles is condition. If your mug is one of the sought after brands, and it is in good condition, no chips, cracks, missing paint or other damage it may have some value to collectors.