Is it okay to incorporate the old mulch that is in my flower beds into the soil?

Is it organic material, like peat moss, or tree bark ? If so, yes you can it will decompose and make nice humus into the soil. An excellent condiment for the soil

Is it okay to incorporate the old mulch that is in my flower beds into the soil?
Yes,it will break down over time making new soil and fertilizer.
Reply:Of course. Mulch actually helps to feed plants as it breaks down.
Reply:sure, since is not full of trash or quimicals!