When you have an Xbox gift card worth 15 and are looking to sell it, there are several options available.

One place you can consider is online marketplaces. These platforms allow you to list your gift card for sale and connect with potential buyers. You need to create a detailed listing that includes information about the card's value, expiration date if applicable, and any other relevant details. Be cautious when dealing with strangers on these platforms and make sure to follow the platform's security guidelines to protect yourself from fraud.
Another option is to ask your friends or family if they are interested in purchasing the gift card. They may be in need of an Xbox gift and could be willing to buy it from you at a fair price. This can be a convenient and straightforward way to sell the card without having to deal with the uncertainties of the online market.
You could also look into local gaming communities or forums. There might be members who are interested in buying Xbox gift cards. Posting in these communities about your available 15-dollar gift card can attract potential buyers who are part of the gaming circle and are more likely to trust and engage in such transactions. Just make sure to communicate clearly and abide by the community's rules regarding sales.