Firstly that cage seems on the small side for 2 Holland lops. Are they babies? It may be okay while they are small but they will need more room when they are fully grown – especially if they are going to spend a lot of time locked in it which they will be for at least 7h a day while you’re asleep. They will need plenty of exercise time in a much bigger space.
http://rabbit.org/faq-housing/ this is a great article about housing from the house rabbit society. They recommend that the cage should be 4-6x the length of the rabbit at full stretch and the bunny must be able to stand to full height in the cage.
As for toys in their exercise area bunnies love cardboard boxes with holes cut in them, cat tunnels and cardboard tubes are a big hit with loads of buns too. Empty toilet roll tubes stuffed with hay, applewood twigs or any sort of untreated wood they can chew on. Willow balls are a favourite of my buns also and are inexpensive in a range of stores.