The first one I am posting is the
Hide Ito Icon Pack (free to use, credit not required, noncommercial only - if you do credit, credit "Hideki Ito"). He didn't put any limits on editing them in our conversation.
Ito was the #1 artist in the mac icon community back when it was thriving. Dude made tons and tons of really neat art, and won a ton of contests. I talked with him, and he agreed to let me upload a compilation of his art on this forum for anyone to use in (noncommercial) games.
This package has over a thousand individual pieces, all 32x32. A ton of these are perfect as item icons, and depending on scale a lot of them would make for nice map doodads too. These were released in batches of multi-icon sets over the course of a couple years. I've excluded a few icons that are tied to a company's IP (so sadly the 25 furbies aren't making the cut), and stuff that was just like, icons pictures of normal computer folders.
This is a zip file, split into loosely-themed folders, with every individual image as a separate png or gif. Most of the images have descriptive filenames, all filenames should be unique (due to a quirk of converting files from old mac filesystems to modern ones, some of the descriptive filenames were lost).
Generally, these are all modern, everyday recognizable items. Some examples:
Bell:

Cauliflower:

Gas can:

Cowboy hat:

Nail clippers:

A house*:

There's over 300 different food sprites alone.
I'm going to update sporadically whenever I turn up anything else neat. If you come up with a good weird source of free-to-use doodadable stuff I won't mind if you posted a link to it here and made this into a doodad warehouse.
*More on these later. Because of the Icontown project there were a lot of artists doing buildings in this style, size, and perspective, and I might be able to get permission from enough of them to have a whole isometric city.