Uneven lumpy forehead. What could be done to fix this? (Photo)

Fillers could be used to fill the shadow between your brows and upper forehead.  If you want a more permanent option you could have a cranioplasty where the forehead skin is lifted up and bumpy portions are drilled down and bone cement could be used to fill in any areas of depression.  The most expensive option is a custom, CT-guided forehead implant which probably isn't worth it in your case. Best of luck! 

Based on the photos most of your forehead irregularities are due to uneven bones. This can be treated with  bone shaping through incision placed along hairline and barely visible. Residual irregularities can be further camouflaged with augmentation using your own fat or artificial material. In person evaluation with a board certified plastic/craniofacial surgeon is recommended. Good luck.

Thanks for posting your photo(s) and inquiry.
Fat transfer can smooth out any irregularities of the skin sometimes this has to be combined with a procedure known as subcision.  A nonsurgical means of dealing with irregularities is filler injection like hyaluronic acid.
I hope this helps.  Always seek consultation with a board certified plastic surgeon and preferably one who is a member of the American Society of Aesthetic Plastic Surgeons.
Dr. B