Given the size and thin/elongated ilia as well as the urban location, I think a domestic cat and/or a raccoon are likely candidates. I'm leaning toward cat.
Ventral view of domestic cat pelvis; Source: BoneID
Anterior view of raccoon pelvis; Source: BoneID
I'm not an expert in differentiating these two ...
That's likely a raccoon and a dead fish (salmon, perhaps).
For the animal on the left: notice the ringed tail, foot anatomy, and lighter foot color, and variable (light/dark) fur color:
University of Arizona
University of Nebraska-Lincoln Extension
Note: Since you mentioned opossums, I include the above to show the vast ...
From the location of purchase, conical shape, color, and size, the tooth is that of a sperm whale (Physeter macrocephalus). Sperm whales have 17-29 teeth in the lower jaw that range 3-8 inches (see Perrin et al., 2009). Their teeth were most often used as scrimshaw, and many can be seen at the Nantucket Whaling Museum.
Just as an FYI, under the Endangered ...
Looks to me like an allium, but you'll find many of these look quite similar at this stage, I doubt you can get much further than that. See for example a Google image search for allium+flower+seeds (added 'seeds' to the search to get later stages like the one you've got).
Alliums include onions and garlic (both cultivated versions you'd commonly find in a ...
I agree with @BryanKrause that this is an Allium seed head. The seed pod and seed on the end give it away
For another partial match from a commonly cultivated plant in domestic gardens, Agapanthus seed heads look similar, though the seed pod and seeds are elongated and winged. When these dehisce at the end of seeding you can be left with a head that ...
The size (~2 inches), broad "quadrate" head, and long posterior abdomen leads me to believe this is a relative large larva of a Predaceous Diving Beetle (family Dytiscidae).
The larvae are sometimes called "water tigers" due to their large mandibles and voracity as aquatic predators.
One possible example:
Dytiscus marginalis; Sources:...