Yup, most likely bored and looking for entertainment or an outlet for energy. Do you walk here often? I walk my Lab pup 3 times a day. He is a digger as well, and when he's bored he will do it, but if he has enough attention and stimulation, he won't.
There could be something underground in that spot in the yard that she is trying to get at, like a mole or groundhog that she can smell.
A couple solutions that I have heard of. You could make the spot into a dedicated digging area. Creat a sand pit that is fenced off with railroad ties where she is digging and praise her when she digs there but chastise her when she digs elsewhere. Hide bones or other interesting toys to encourage her to keep digging in that spot so that she does'nt start digging elsewhere. This will allow her the pleasure of digging while keeping the rest of your yard intact.
You could also try burying chicken wire where she is digging as dogs do not like the feel of it on their paws. Unless she is a really hard dog, which my Lab is, it would probably stop her. My Lab would just chew or play with the chicken wire until he had removed it and continue digging.
Also try playing with her more or walking her more. Try some stimulating games like hide and seek, or teaching her how to retrieve. Maybe teach her some new tricks. Most dogs just want to spend time with their masters, being social creatures, so behavioral problems can develop when the are'nt getting enough attention. Good luck.