The few Commemorative coins listed below were minted in larger quantity and released for general circulation at face value. Some of them are more difficult to find in Mint Uncrculated state than the other commemorative issues which were Non Circulating Legal Tender (NCLT) coins and since 1991 have been sold at a premium by the Central Bank. See some comments.
1957 Buddha Jayanthi - 2500th Anniversary - Rs 5 coin - Rs 1 coin
1968 U.N. Food and Agriculture Organization - Grow More Food - Rs 2 coin
1976 Fifth Non-Aligned Summit Conference - Rs 5 coin - Rs 2 coin
1978 First Executive President J. R. Jayewardene - Rs 1 coin(s)
1981 Universal Adult Franchise - 50th Anniversary - Rs 5 coin
1981 Mahaweli Development Scheme inauguration = Rs 2 coin
1987 International Year of Shelter for the Homeless - Rs 10 coin
1992 Second Executive President R. Premadasa - Rs 1 coin(s)
1995 United Nations - 50th Anniversary - Rs 5 coin
1995 U.N. Food and Agriculture Organization - FAO 50th Anniversary - Rs 2 coin
1996 United Nations Children's Fund - UNICEF 50th Anniversary - Rs 1 coin
1998 Sri Lanka Independence - 50th Anniversary - Rs 10 coin and Rs 200 note
1999 Cricket World Cup - 1996 World Cricket Champions - Rs 5 coin
2001 Colombo Plan - 50th Anniversary - Rs 2 coin
2003 Syamopasampada - 250th Anniversary - Rs 5 coins
2006 Buddha Jayanthi 2550 B.E. - Rs 5 coin
LakdivcCoins Collection website.