Agitation for initiative and referendum in Michigan started in 1895 with support from Detroit mayor and later governor Hazen Pingree. Thirteen years later in 1908, I & R finally made it into the state constitution. It first proved unworkable and in 1913 a better one came in during the administration of Governor Woodbridge Ferris. The procedure provided that 39,000 signatures could get a constitutional amendment initiative on the 1914 ballot. But it was not till the 1930s that initiatives actually won voter approval. The first initiatives established a liquor control commission, limited property taxes, specified that gas and vehicle weight tax money must be used for roads, and established a system for nonpartisan election of judges. In the 1940s, voters enacted one to ensure that part of the state's sales tax revenues was returned to the municipalities, and another proposal that modified the property tax limitation. The initiative for which Michigan is most famous is the "Bottle Bill," approved by a 2-1 margin in 1976, which put a 10-cent deposit on bottles and cans. Initiatives and referenda through 2008, which made it to the Michigan ballot, are listed here: http://www.michigan.gov/documents/sos/Const_Amend_189834_7.pdf 
See Ballotpedia.org for more information about Michigan's Initiative and Referendum history: http://ballotpedia.org/wiki/index.php/History_of_I%26R_in_Michigan