I found some little flower pots on clearance at jysk, like, teacup-sized. I'll have the kids paint them and we'll plant some flowers in them, I think. For the little ones, I'm planning on helping them put their handprint on it.
I've started a bunch of vegetable seedlings with the older kids and they've been very into helping me water them, so it's kind of a continuation of that. The kids are excited to plant and water their own plants, and hopefully the moms will think they're cute.