[JustaDumbBlonde]

"Would it be better to till the compost into the top 6" of the beds, or should I spread it as a top dressing after planting everything???"

Don't know. How deep are your beds? What kind of soil do they contain? What was your goal with purchasing the mushroom compost?

[Petruchio]

How deep are your beds?

The beds are 4'X4' and 1' deep. Here is a pic from last year

What kind of soil do they contain?

When I built the beds, I ordered a truckload of topsoil. It was real heavy, clay like, so I added a lot of peat moss and sand.

What was your goal with purchasing the mushroom compost?

Now 14 years later I wanted to add a bit more plant matter to boost the health of the soil. The soil test said it was weak on plant matter.