Although Omni Core is able to find transactions from the initial OMNI (MSC) crowdsale and uses them to compute OMNI balances of participating addresses, there appears to be no JSON-RPC method that returns these transactions. omni_getcrowdsale would be a likely candidate, but omni_getcrowdsale 1 true returns: No information available about transaction.

omni_getcrowdsale returns an array named participanttransactions which contains the following information for each transaction for other crowdsales (e.g. MAIDSAFE omni_getcrowdsale 3 true):

{
    "txid" : "4ec15360a03d23c069c2fd4a035cfee28af5ddfdd5a6839934dd2629129d477e",
    "amountsent" : "100.00000000",
    "participanttokens" : "485781",
    "issuertokens" : "0"
}

I propose the following two enhancements:

A. Extend the existing omni_getcrowdsale method to support propertyid 1.
B. Add blocktime and sendingaddress to each transaction object in participanttransactions

I'm not sure if the initial crowdsale exactly maps into the return object for omni_getcrowdsale (e.g. closetx doesn't apply) but it is probably close enough.