The exchange rate between the US dollar and the Nigerian naira is constantly fluctuating. To determine how much 300 US dollars in the form of an Amazon gift card would be worth in naira today, one needs to check the current exchange rate.

Exchange rates are influenced by various factors such as economic conditions, market trends, and central bank policies. Financial institutions and online currency exchange platforms are the main sources to obtain the most accurate and up-to-date exchange rate. By inputting the amount of 300 US dollars into these platforms, the corresponding value in naira can be calculated.

It's important to note that when converting, there may be additional fees or margins depending on the method of conversion. Some exchanges might offer a less favorable rate compared to others. So, it's advisable to compare different options to get the best value for converting the 300 USD Amazon gift card into naira today.