I like moussy's suggestions.

I would use Round-up also just because of the poison ivy. It may even take a couple of treatments. But I would take extra precaution and wear gloves if you are going to remove any rocks, which I would before adding any soil.

You don't say how tall the trees are, but I have daylilies under an oak tree that has a tall trunk, so the plants get a lot of morning and afternoon light. We put a 4x4 wood border around our oak tree.

This oak tree only had grass around it so we sprayed paint where we wanted the border to be, then sprayed roundup a couple of times to clear all the grass. Then I just started planting. There is no mulch around the base of the tree. The picture was taken in the spring so the daylilies haven't begun blooming yet. I probably have about four different daylilies here and plan to put more in this year. Vickie

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I'm not sure why you think your choice is between daylilies and rubber, as there are any number of plants that will do beautifully under trees. The key is to choose the right plants. :) And the choice will depend largely on the species of tree. Some, like the oak in the photo, are deep-rooted enough and with branches high enough that you can grow many things, including some flowering things. Others, like shallow-rooted, thirsty maples or magnolias with their deep shade under the canopy, will probably be somewhat more to highly challenging.

Regardless of what you decide to plant, my advice is to be very careful about filling a border under a tree with soil. You will want to make sure that any surface roots remain UNCOVERED by soil...from what I have read, it is possible to kill even a mature tree by doing that.

I believe I have a Maple tree. I went on the tree forum and asked about trees that shed the helecopter seed pods and most stated they thought this was a maple tree. On one of my trees (the maple), there are already daylillies planted around the trunk of the tree. They are not in a flower bed. I want to do this for other tree, I mainly like the folliage that surrounds the tree from the daylillies.

If you are looking for foliage, then ferns or hostas would do much better than daylilies.

I second hemlady's suggestion and add that if you're looking for "strappy" foliage, liriope is commonly planted beneath trees here in the Wash DC area. It's tough as nails and can stand the shade/dryness under trees--which daylilies may or may grudgingly stand--tolerates pollution, tourists' feet and even provides small purplish blooms. But I'd also follow Ackerman's advice (fmr Director of the Nat. Arboretum) to not plant an 'ocean of green'--mix it up with those ferns and hostas (esp variegated ones) and it'll be quite pretty.

I know that an oak trees roots are different than a maples, but I have a few more suggestions for some spring flowers that like shade. I am not sure how they would do under a maple tree, but these really brighten my day when I see them blooming.

Spiderwort (next two pics)
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Wild Columbine (Aquilegia canadensis L.) is the red nodding flower on the right. White bleeding heart (center) and Winky Red and White Columbine (left). The oak has a high enough story that even the irises do okay under it.
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I hope you find something to put under your maples for color. These would be great with ferns and hostas, I think.

Vickie

daylillies are great beneath trees. I'd love to see how yours turned out