Reddit mentions of ¡Pío Peep!: Traditional Spanish Nursery Rhymes (Spanish Edition)

EDIT: of course you can't teach your kid to speak Spanish unless you know it yourself. I do think it's worth familiarizing your kid with Spanish anyway. A little exposure to pronunciation at a young age helps a lot with minimizing accent if he learns it when he's older. And by exposing him to Spanish now you're showing him it's something that you value, which makes him more likely to be interested as he gets older.

If you can teach yourself at least enough Spanish to be able to pronounce it fluently, here are some books I really like:

Pio Peep! - it's Spanish nursery rhymes and songs with a non-literal English translation alongside (so don't use the English to deduce what the Spanish means)

Me Gusta Cuando... - sweet bilingual board book with lots of pro-social messages (I like it when you let me help, I like it when we eat new things...)

Buenas Noches Gorilla - there's actually not a lot of text in this one, but it's fun for learning animal names and most 3 y.o. find the story hilarious

Toca, toca books - like baby touch & feel or lift-the-flap books but in Spanish. If your kid is still into books like this, I've liked all of the ones I've bought.

Translations of Dr. Seuss, Eric Carle, Sandra Boynton etc. are a bit hit or miss in my experience. Some are great, whereas some are charmless or have grammatical errors.

And for an older kid with some fluency, or for reading aloud if you learn some Spanish, I like the Geronimo Stilton books en espanol. They're early chapter books but have a lot of word art that helps with understanding what vocab means.