What is past form of place?

As a noun it is 'the place'

As a verb;

Past tense ; placed ; I placed a bag on the floor

present tense ; place ' I am placing a bag on the floor

future tense ; will/shall place. ' I shall place a bag on the floor.

NB 'Shall is used for 1st person . 'will' is used for 2nd and 3rd person.