You can celebrate all Christian festivals! They were all once Pagan!
Yule--Christmas. Imbolc--feast of the circumcision. Ostara--Easter.
Beltane-- Queen of the May. Litha--Pentecost. Lammas--first harvest festival. Mabon--second harvest festival. Samhain--Holloween.
Then there are Holy Days,that became Holidays.Saint days,such as St Patrick's Day, St David's day,St Andrew's Day, St George's Day.