Digging mulberries is never easy, even if the plant is dead. I tried repeat applications of round-up and never did more than set the plants back mildly. I fought these darned things for 18 years. You have my complete sympathy! They're a bear!

The best thing to do is get them out EARLY -- as soon as you see one sprouting, get it out! and get the root or it'll just come back. They're the devil to remove even when small.

Since the ones you have are well past that stage, you just have to dig deep and all around the plant and keep at it but you can get them out. I removed them even as small trees (10' or more) but it was a huge job. If you don't have a shovel with a life-time warranty handle, get one. I don't trust any handle against mulberries :) but the ones I bought (after breaking a wood one) at Sears helped a lot. They're made of fiberglass and are guaranteed against breaking for life, so I figure even if I destroy it I can at least get a new one :) I was able to put more stress on them than a wood handle. A crowbar and pitchfork help, too. Or if you have access you can always try tying a chain around them and pulling them out with a truck, but make sure you know where to attach the chain to the truck so you don't pull it apart.

Another option is to just leave them... after all, the birds love the fruit. I had one on my fence row that I never bothered with (but of course that was the reason I had so many others!).

I tried cutting them off below the soil line and they resprout. They're the most vigorous, persistent, stubborn plant I ever dealt with. Sorry I can't give you good news on an easy way to remove these darned things but I just never found one. Maybe another gardenwebber will have a miracle fix!

Good luck!