Buffy gets this wonderful Cross from Angel in the very first episode. Its the first time Buffy meets Angel... Later when she recognized that he is a Vampire they are kissing passionately in the Bronze and Buffy´s Cross is burning into Angels skin with the words "love hurts". Its symbolic for their relationship.
This ring is a typical Irish ring for friendship or worn as wedding ring. In season 2 Angel gives a Claddagh ring to Buffy for her 17th birthday. In a later episode, another suitor, Scott, also attempts to give Buffy a Claddagh, which she rejects, because it remains her on Angel. She decides than to lay this ring down on the place she killed him...where he later comes back from hell.