Other than tickets, what are some ways to get diamonds for free?

Looks like there is nothing you can do about the movie tickets

Other than tickets, these are the ways to get free diamonds:

• Chests - These show up randomly around your farm, the ocean next to your town, and other people's farms. Sometimes they are locked, and sometimes they provide up to 8 diamonds for free.

• Derby Rewards - If you complete enough derby tasks to gain a horseshoe for your neighborhood there is a chance that you can get diamonds as an option for your reward.

• The Mine - Occasionally, excavating ores from the mine will grant you a diamond in addition.

• New Fish - This is the only reliable way to get free diamonds besides the movie ticket, though the supply is limited. Every time you catch a new type of fish with a lure (or a new size of a fish you've caught previously), you can visit the fishing shack to look at the book of the fish you've caught. Tapping on the picture for any new fish will grant you up to three diamonds.

• Mid-level Thresholds - You get a random reward for reaching 25%, 50%, and 75% of the XP you need to level up, and that random reward is sometimes diamonds.