Waaaa! I'm soooo jealous right now. I'm one of those you describe at the beginning of your post: drooling over seed catalogs and wishing it was spring again already :0)

I love spontaneous births of plants, like you had with the tomatoes. You completely forgot about them, and suddenly they are there.
Last year I had 3 Tomatillo plants in the garden. We didn't like the fruit, so we decided to grow other plants to replace them. But this year, out of nowhere, 3 tomatillo plants popped up - nowhere near where the plants had been.