Yellow-leaved form of Petasites.

Okay, so I looked up Petasites and it does look like it. However, it says it can be invasive and it grows huge! Is it a good plant to keep in my garden? If you think I should keep it, I definitely need to move it because it's in a small space.

It's a gold leafed sport of a NW native plant, so "invasive" would not be the correct term to use :-) But it does spread to form an impressively sized colony if happily sited - drier conditions will keep it on the smaller side.

Yours looks like Petasites frigatus var. palmatus 'Golden Palms', golden western coltsfoot or butterbur. And you'll find that many of the plants available at swaps and plant exchanges are robust spreaders -- that's why folks are so generous with them!!