We've used a couple of city parks, works great. One we stayed at a few years ago was in Dumas TX (one night), they had "free" elec and access to public restrooms. They did have a donation box as well, we did leave a donation.
Another one was in O'Neill NE (one night there), that one had water and elec with a dump station right there. Couldn't find a donation box so we went to city hall, we ended up not donating but can't remember why (?????) Stayed there last August.
Dan