My mother-in-law was a single parent, so for Father's Day we got her a card and some flowers.
It just makes sense. She did all the parenting, so she should get all the parenting holidays. Besides, we like her and any excuse to give a little present is a good excuse. What the heck, giftgiving is fun!
It's extra easy for us, since she's living in a (literal) mother-in-law apartment in our house. She's the perfect housemate since not only does she help out around the house and tolerate our bad habits, she spends most weekends at her boyfriend's. We had worried a little bit about whether we'd all get along since there had been a normal amount of parent/child conflict, but it seems that now that we are all over 40, a lot of the teenage sturm and drang seems just silly.
There are many practical advantages to having an additional housemate. It's very handy to have an extra adult to share chores. Since she moved in, at dinner time we have 50% more people to help make food and carry the conversation. On the rare occasions where no-one is up for cooking, we hit Proletariat Pizza in White Center, which has not only some of the best pizza I've ever enjoy, but also a fine Tiramisu which is best shared among three (pictured).
Getting the flowers live was a pretty obvious move; in the past, we've swapped seedlings but what with the move an' all, this year I'm way behind on planting. So for Father's Day, The Lovely Wife and I stopped by the West Seattle Farmer's Market and picked up some seedlings. She doesn't know about them yet (still at boyfriends) but it'll be a nice surprise for a mom who, having done the work of two parents, should reap the reward of two holidays.