When did you guys have your babies sleep in toddler beds?

My daughter is 1 now and has been bed sharing with us for the past 4 months. I suspect she likes sleeping in an "adult" bed much more then she does in her own playpen (my mom did sow some stuffing together to make a "mattress" for her playpen). She sleeps in her own playpen during nap time but won't sleep in it at night.

Some mom's told me that they put a mattress next to their bed as a way to get their baby to sleep...

I know 1 is probably too young but I'm looking for suggestions!