Not only can animal rescue organizations use donation money, they could use supplies too!
Consider donating items like fleece blankets (they can cut them up to size for the animals they care for), big garbage bags, paper towels, rakes (for mucking stalls/pens), etc.
Call your local org ahead though and ask if they could use the items you're considering dropping off. Some orgs have amazon wish lists which makes it much easier to get them what they need.
Here are links of random 'wish lists' to give you an idea of what sorts of things orgs like this request:
http://www.southfloridawildlifecenter.org/donate_animal_supplies
https://www.wildlifeimages.org/give/wishes-for-wildlife
http://www.wildthingssanctuary.org/wish-list.html
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