All her life my dog has been well behaved. Never got into trash until now. What’s going on? Why is she doing this now?

I wonder whether it's you who have bnecome too relaxed when it comes to your dog.  Perhaps.   Also for some reason, maybe being left alone at home and getting bored?, she did it once and found it great fun!!   Now this is happening, you just have to upgrade your trash bins so she can't get into them.

You need a different kind of trash can.

My dog used to pull the tissue out of the trash can.  We peppered the trash with chili powder & that has stopped her from stealing the tissues.  Any kind of pepper would work.

You don't say how old she is but dogs who feel they are lacking in nutrients can start doing this but also dogs who feel they have a health issue.   My dear old boy is now eating dirt in the garden.   He has a periodontal tumour and is coming to the end of his life.  He obviously feels that he is gaining something from the dirt. 

If the dog is old and this is happening often then look at what you're feeding him or take him to the vet for a check up

you can put it inside a cupboard

It's true nature has been unlocked.

It doesn't want to be a lap mutt

Has something changed in her life that upset her?

No way to tell specifically.  But in general dumping trash is a way to get attention.  She wants something.  Now it's up to you to figure out what it is.

For my dog, Boots, she'd over turn the trash can in the family room when she was hungry for snacks.  She taught herself that behavior; I have no clue how she did that, but she figured out the cause and effect relationship between dumping the trash and getting my attention.

Dogs are opportunitists, which means they take the opportunity when/if they can to 'find' a toy/ food in the bin.......and it only takes ONE time when they have been successful and they continue to take advantage of you not emptying the bin in the hope they 'find' it again..... so until now she has been kept busy, not been bored or simply has not taken the opportunity...now she has and will continue.......... so empty your bin each and every time or put it out of her way as she will continue

Dogs are known to get into the trash every once in awhile, and even to eat the ... in outdoor dogs because they are able to ingest spoiled food or waste as well as ... Today she threw up a plastic roll sausage wrapper with the metal clips on the ... seizures from something they ate and never have seizures again in their life.