From the Sources
Eliezer comes to Betuel’s house and Betuel offers him food. Eliezer says that he won’t eat until he has explained the whole story of why he is there. This is lucky because the Midrash notices that after Eliezer speaks we do not hear from Betuel again. It therefore concludes that he must have died. It says that even though he said that he agreed to the match, Betuel really did not want Rivkah to marry Yitzchak, so he tried to prevent it by killing Eliezer by putting poison in his food. Whilst Eliezer was speaking, a Malach came and swapped the plates over. So Betuel ate his own poison and he died.
How to eat it
DO NOT POISON YOUR GUESTS!!!!!!! However, my kids made a pun and suggested we use “poison-berries” (boysenberries).