Michelle,

Your best source would be the Google Sketchup Warehouse.
Using the prefix filetype:zip you can find models that you can import directly into SH3D.

Examples: horse, dog, cat, etc

If you can't find what you are looking for, leave out the prefix filetype:zip. You should then load the models in Sketchup and export them in the 3D DAE/Collada format suited for SH3D.

Hans