There is a legitimate scholarly difference surrounding this issue. Those who hold such celebrations as forbidden do so contending that such celebrations are “religious in nature” and amount to imitating the religious rites of others.
Those who contented that such celebrations are permissible, do so contending the opposite: such celebrations are not religious in nature and that the origin of things is permissible unless explicitly forbidden. Sheikh al-Qaradawi stated, concerning Mother’s Day, there is no way he considered it forbidden. He based his contention on the legal axiom: “Nothing is made forbidden except with a clear text.”
It is well known that al-Rajabiyah was a holiday observed by the Arabs before for the time of the Prophet [may Allah's peace and blessing be upon him] up until the third century A.H. and the jurist differed on its ruling. The Hanabali’s considered it permissible, while the Malikis held it to be disliked.
The Indigenous Imperative
As a convert to Islam and based on my humble legal training, I agree with the second opinion. Many of us, those of us who have converted to Islam, can use these moments to share the beauty of our faith with our families and loved ones in an non-hostile environment. Perhaps, by giving gifts to our parents we can heal wounds, build relationships and move forward. At the same time, such celebrations are based on the foundations of our faith: honoring one’s parents. Therefore, we should engage such holidays with the intention of fostering noble relations and spreading the beauty of our faith with others.
Allah knows best