I never used to feel right about asking someone can I dig in your yard so I just would do the park thing and anywhere I could find public land but that gets old after awhile just digging newer coins and a lot of trash but once I started doing the research(a must do IMO) you’ll see that to hunt on good sites 9 out of 10 times you need someone’s permission,just always be polite,present yourself well and and give a brief explanation of what you do and why you do it I always offer that anything I find related to the property they are welcome to have it and anything of value I will split 50/50 with them and most importantly always say thank you wether its a yes o