Donations, particularly those in the context of you providing a free service (software, libraries, etc.) are a notable grey area in tax code.
Simply naming a button "Donate" doesn't necessarily classify the money transfer as a "gift". The IRS can decide that it's money you're being paid to continue your excellent work/service, making it taxable income (unless you're a registered non-profit organization).
In the instance of Patreon, and many other crowd-funding services, you're providing a certain level of "service" for each tier of donations (such as early access or something, I'm not sure what you're offering), which means they're receiving consideration for their donations, which most likely makes it fall into taxable income (again, unless you're a registered non-profit organization).
State tax law is even more convoluted, and you should consult your tax professional for clarification on your specific situation.