I've been seeing quite a few of these little brown creatures hopping rapidly around the greenhouse recently. I believe they're American toad(let)s. To give you an idea of scale, here's the same toadlet with my index finger. (Very obliging of it to sit still for this photo, I thought. Also, note the cleanliness of my nail - you can tell this was taken before I did my daily hour of weeding.)
I think toads have an undeservedly bad reputation. A prime example is to be found in the opening lines of Philip Larkin's poem Toads. They have been in my mind since I started noticing the toadlets (although I was convinced that the poem was by Ted Hughes - sorry Philip). I first read the poem at school and have only just reread it now. I appreciate its message more these days than I did when I was seventeen!