Tools you need :
1) Cheat Engine 5.5 or Here
3) Flash Player 9 (IE and non-IE)
1) Water your plants or create a new farm plot.
2) Open your cheat engine for process list and choose internet explorer.
3) Scan 5D8B00000564840F with Hex, 8 Bytes and also read memory.
4) Scan 738B000000F6840F with Hex, 8 Bytes and also read memory.
5) Copy the results and paste it into the code generator below and click Enviar.
Note: you are able to choose 10,000 / 25,000 / 75,000 / 100,000)
6): You will see a list of code generated. Simply copy the whole chunk of code.
7 ) Go back to cheat engine > Click memory view > Select Tools > Autoassemble
8 ) Paste all the code into the Autoassemble and click execute.
9 ) Start watering your farm plots and you will receive your water trophy as well as your coins.
*Note: Water your plant once after you execute your code. Once done, save it.
Source: Patiniox Blog