On my first Mother's day as a mum, me, my son, my brother, and my parents went out for a meal together. It was really nice because being a single mum it was really thoughtful of my parents to organise something.
In the years since OH and I have been together he (we) always organise a meal for the three of us, my parents and brother, and his mum and husband (although sadly he passed away last November). Most years OH's sister and her partner come up as well. It's always a really nice afternoon.
Don't get me started on this year though, it's a very touchy subject!