Be careful trading these, there are some odd side effects.
1) The FF rate is determined by the *average* rate for the month. So, if the fed meets on the 29th of the month and changes rates, the FF contract expiring that month will not move very much.
2) I've now had problems with both IB and Man Financial trading FF options. Both had programmed their systems with the mutliplier for the percent (i.e. the multiplier for the futures contract). However, options are quoted in basis points, not percent. A $625 option straddle was charged to my account at $62,500. Man's solution was to pretend options are quoted in percent and fix my fill price. IB is still quoting basis points. Nothing like confusion...