If you are missing some crops, simply go to a friend's farm and find his or her roadside shop and tap on it and see what they are selling. Or if your level 7+, open your newspaper and see what's being sold.
Cats and Dogs
You can buy the cats and dogs with vouchers and you gain vouchers from completing boat and truck orders or harvesting crops and treasure box. You can not trade them. When you have enough vouchers you can buy your cat or dog, but before you do this you must buy a cat or dog house. Your cats and dogs will need feeding, milk for cats and bacon for dogs. Every time you feed your pet you will get 30 xp. They only feed every few hours. Apart from the xp they are mainly a decorative purpose for your farm; for some players, this will be a personal achievement getting each individual pet.
Earn Diamonds
Open your mine and use TNT. It will produce diamonds every couple of blasts. When you have enough diamonds, pay for Tom's service and have him find nothing but TNT and load up on it. Then blow the mine and use as much metal as you can; again, more diamonds will come every couple of blasts. Sell what metal you can't store. But you have to use Tom and get a bunch of TNT.
Easy Gold
First go to the roadshop and buy a new slot. Then on the one you bought, sell five pieces of wood and if anyone buys it, you will have 500,000 gold. Keep in mind; this glitch only works once.
Fast XP
Want to get fast XP? If you are level fifteen or up and you have apple trees, make sure you pick the apples as you will get 7 XP per apple. Try and find apple advertisements in the paper, then visit the people that have apple advertisements, then search their farm for shaking trees with exclamation marks on a sign. Click on the sign and you get an XP reward. Complete orders on the order board. Visit other people's farm and look at their dock; if it has a crate with an exclamation mark, click it and take a look at the supplies you need to get an XP reward.
Finding Missing Crops
If you have run out of a certain type of crop, go into your friend's tab and select Greg. Enter his roadside shop and buy everything that is there. Sometimes there is even some tools there for a very low price. If Greg does not have what you want, visit other farms and go thought their newspapers and buy what you need in bulk (like 10 wheat for $x).
Free Stuff
Buy a lot of wheat until silo is full, plant half of it, then turn your device up right and shake it while cutting down wheat. You will get free items.
Roadside Shop
Provided you have an available slot, you can sell stuff at the roadside shop as often as you want. You can only get a free advertisement in the newspaper every thirty minutes.
Wood Panels
These can either be found in the treasure chests or you can buy them with your diamonds. A good place to find them is when you are harvesting crops as they will just appear and go into your barn.
Buying Missing Crops...