I am sure that just about anyone, public or private, would be happy to have you pick bitter (sour) oranges before they start falling and making massive messes. Years ago, some stopped at my house and asked to pick them for marmalade. I was delighted. They picked 'em and I didn't have to clean up the yard.

Can be found as "street trees" near the capital, and near Encanto park. Older neighborhoods mostly.

I used to have a house with three of them, and marmalade-making friends stripped them every year.

Look for slender-trunked trees, pruned fairly high, with small to medium sized oranges that have a thick, dimpled skin. They are less likely to sunburn than the AZ Sweets.

Thank you. They are exactly as you described. I found some pruned high, with dimpled skin. Very sour.

Don't know about in Phoenix, but I've found them easily in Tucson a few years ago, around the University campus and in some parks in the same area. Yes they are were very sour, but I thought the flavor was much better than a sweet orange, right about this time of year... Also some great olives still on the trees at that same time!