We have some really great user created mods in the mod section of the forums
here. Just be sure to read the sticky post on
how to install them before using any of them.
Yes, the flowers are by Lewanda. Most of the mods I use are - I love her work!
For help with the shed and other stuff, see
this post. I don't really know that dropping them on the ground is such a good way to try for the trophy. The activity is random and you could be dropping them 5, 10, or 500 times before it ever comes up. In my opinion, you're better off just playing the game and listening / watching for the kids to do it on their own. But, if you want to try dropping, I suppose I would do it in the area above the birdbath, on the grass where the gopher holes show in the screenie I posted.