You can Spin Dr. Abawuwu's Wheel everyday once for free. Additional spins will cost you 1 shroom.
There are 10 possible outcomes:
Lesser Wood Reward
Greater Wood Reward
Lesser Stone Reward
Greater Stone Reward
Lesser Experience Reward
Greater Experience Reward
Lesser Gold Reward
Greater Gold Reward
1~3 Shroom Reward
Random Item (usually a common level equipment)
**Note even if you do not have a fortress, or if your resources' capacity is full, you will still receive the resource award.
It's speculated all rewards are scaled with your level. **[further confirmation is needed]