JETX said:sorry... but WRONG!!
A '3-day notice (to pay or quit)' applies only to non-payment of rent. Since there is not an agreement to pay rent at all, it wouldn't apply. Further, absent any rent 'due date', the lease is considered to be weekly.
Applicable Florida Statutes:
83.01 Unwritten lease tenancy at will; duration.
83.02 Certain written leases tenancies at will; duration.
83.03 Termination of tenancy at will; length of notice.
83.04 Holding over after term, tenancy at sufferance, etc.
at: http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&URL=Ch0083/ch0083.htm
Where did it say in that Statute that because there is no rent due date that it automatically converts to a week to week tennancy? Op's mother could very well argue that she has been there for 6 months and it was a month to month tennancy. Tha absents of rent does not make it a week to week tennancy automatically.
The only way it does is if the tennant is a worker for the landlord and he is receiving his place to live for part of his pay. Then it converts to whenever the tennant is paid. If tennant is paid weekly it is a week to week tennancy if paid monthly then it is a month to month tennancy.