It feels kind of off when you cut grass and it gives you meat...maybe make a grain food? (It would still do the same thing, it would just look different).
There's meat and coins in the grass and dead minions give you wood logs, seems legit... :D
I think with dead minions you're stealing their broken weapons. That's where the wood comes from. As for grass, I don't understand it either but if it's grain they shouldn't add blood toward upgrades.
Well, this guy sort of sums it all up:
Customer support service by UserEcho