Without reading PL's answer, I may be duplicating here, but do want to stress that MONEY isn't the best thing to send a California inmate. The reason is a substantial portion is deducted (40% or more in some places) to "reimburse" the state for the prisoner's upkeep.
snacks and candy. that's what my bff sent to her grandson when he was in prison. And she bought him a TV, but it has to be one of those prison issued TVs that are clear see -thru plastic.