Personally, I think the birthday of a boy you like is a great opportunity to send him a gift to express your feelings. You can choose some ambiguous gifts that are usually only given between lovers, such as various couple gifts or chocolates.
First, since it is the boy you like, why not send him a small gift on his birthday to express your feelings? A practical wallet can be customized with engravings. The phrase "If you are well, it will be sunny" is the warmest and most touching language in the world. If you give your sincerity as a birthday gift to the boy you like, there should be few boys who would be willing to refuse it!
Second, I think chocolate is a must-have choice for birthday gifts for boys you like. Chocolate is a traditional gift for lovers to express their love. You can choose heart-shaped chocolate packaging or chocolate that can be engraved with words, such as happy birthday or I love you. In short, a box of heart-shaped chocolates is enough to let the boy know what happened.
Third, if you want to express your feelings in a subtle way, you can also give a watch as a gift. Generally speaking, giving a watch to the opposite sex means that you want to be with you every minute. Choose a style that suits his temperament. Boys like watches. A gift like this can not only show your feelings but also easily win the boy's love.