Isn't if tunny when your child will eat something at Daycare or School or Grandma's house, but won't eat it at home? and by funny i mean, frustrating.
On the one hand you are relieved that he is trying something new, but then it is frustrating because all you can ever get him to eat are the same five things. 
I get it, it's the same reason we attach feelings and moods to certain food. We don't totally let that go; cinnamon hearts on Valentine's Day, Turkey at Christmas, cookies in bed..teehee. This is especially the case for little minds that are just putting the world together and making connections.

Perhaps this is one of the highlights of getting them out and around other people and places. It exposes them to new adventures, other ways of seeing the world and attach new meaning and emotions to food. It gets them to try new things.
Speaking of which, the cauliflower pizza crust was a hit last night. Husband and kid approved. One more entry for the cookbook!