@Jessica Muto, there is a way to do this, but not too many Realtors will understand or be familiar with it (which might not help much on MLS listed properties). You can utilize a 1-2 page, non-binding letter of intent that specifies the key negotiation points (location, price, dates, contingencies) and specifies the contractual form to be used (likely the C.A.R. Residential Purchase Agreement). You can do this on your own, without involving a Realtor for the offers.
Remember that if a property is listed on the MLS, the seller has agreed to pay the seller's agent a commission and the seller's agent (by virtue of other agreements with the Realtor association and the MLS) has agreed to pay the buyer's agent a certain split of that commission. Thus, if you're going direct to the seller's agent, you should be able to negotiate a lower purchase price, potentially via a lower commission for the seller's agent (since no buyer's agent would be involved). However, you would not have the representation of an agent (or the seller's agent might try to act as a dual agent, which is probably worse).